Perhaps one of the easiest descriptions of the Unitive State is from St. Teresa of Avila. I shall let her share her experience here without comment. Again, this is all in her definition of the Fifth Mansion.

 
1.
      You may imagine that there is no more left to be described of the contents of
      this mansion, but a great deal remains to be told, for as I said, it contains
      favours of various degrees. I think there is nothing to add about the prayer of
      union, but when the soul on which God bestows this grace disposes itself for
      their reception, I could tell you much about the marvels our Lord works in it.
      I will describe some of them in my own way, also the state in which they leave
      the soul, and will use a suitable comparison to elucidate the matter,
      explaining that though we can take no active part in this work of God within us,173  yet we may do much to prepare ourselves to
      receive this grace. You have heard how wonderfully silk is made—in a way such
      as God alone could plan—how it all comes from an egg resembling a tiny
      pepper-corn. Not having seen it myself, I only know of it by hearsay, so if the
      facts are inaccurate the fault will not be mine. When, in the warm weather, the
      mulberry trees 130come
      into leaf, the little egg which was lifeless before its food was ready, begins
      to live. The caterpillar nourishes itself upon the mulberry leaves until, when
      it has grown large, people place near it small twigs upon which, of its own
      accord, it spins silk from its tiny mouth until it has made a narrow little
      cocoon in which it buries itself. Then this large and ugly worm leaves the
      cocoon as a lovely little white butterfly.
    
   
2.
      If we had not seen this but had only heard of it as an old legend, who could
      believe it? Could we persuade ourselves that insects so utterly without the use
      of reason as a silkworm or a bee would work with such industry and skill in our
      service that the poor little silkworm loses its life over the task? This would
      suffice for a short meditation, sisters, without my adding more, for you may
      learn from it the wonders and the wisdom of God. How if we knew the properties
      of all things? It is most profitable to ponder over the grandeurs of creation
      and to exult in being the brides of such a wise and mighty King.
   
   
3.
      Let us return to our subject. The silkworm symbolizes the soul which begins to
      live when, kindled by the Holy Spirit, it commences using the ordinary aids
      given by God to all, and applies the remedies left by Him in His Church, such
      as regular confession, religious hooks, and sermons; these are the cure for a
      soul dead in its negligence and sins and liable to fall into temptation. Then
      it comes to life and continues nourishing itself on this food and on devout
      meditation until it has attained full vigour, which is the essential point, 131for
      I attach no importance to the rest. When the silkworm is full-grown as I told
      you in the first part of this chapter, it begins to spin silk and to build the
      house wherein it must die. By this house, when speaking of the soul, I mean
      Christ. I think I read or heard somewhere, either that our life is hid in
      Christ, or in God (which means the same thing) or that Christ is our life.174  It makes little difference to my meaning
      which of these quotations is correct.
    
   
4.
      This shows, my daughters, how much, by God’s grace, we can do, by preparing
      this home for ourselves, towards making Him our dwelling-place as He is in the
      prayer of union. You will suppose that I mean we can take away from or add
      something to God when I say that He is our home, and that we can make this home
      and dwell in it by our own power. Indeed we can: though we can neither deprive
      God of anything nor add aught to Him, yet we can take away from and add to
      ourselves, like the silkworms. The little we can do will hardly have been
      accomplished when this insignificant work of ours, which amounts to nothing at
      all, will be united by God to His greatness and thus enhanced with such immense
      value that our Lord Himself will be the reward of our toil. Although He has had
      the greatest share in it, He will join our trifling pains to the bitter
      sufferings He endured for us and make them one.
   
   
5.
      Forward then, my daughters! hasten over your work and build the little cocoon.
      Let us renounce 132self-love
      and self-will,175  care for nothing earthly, do penance, pray,
      mortify ourselves, be obedient, and perform all the other good works of which
      you know. Act up to your light; you have been taught your duties. Die! die as
      the silkworm does when it has fulfilled the office of its creation, and you
      will see God and be immersed in His greatness, as the little silkworm is
      enveloped in its cocoon. Understand that when I say ‘you will see God,’ I mean
      in the manner described, in which He manifests Himself in this kind of union.
    
   
6.
      Now let us see what becomes of the ‘silkworm,’ for all I have been saying leads
      to this. As soon as, by means of this prayer, the soul has become entirely dead
      to the world, it comes forth like a lovely little white butterfly!176  Oh, how great God is! How beautiful is the
      soul after having been immersed in God’s grandeur and united closely to Him for
      but a short time! Indeed, I do not think it is ever as long as half an hour.177  Truly, the spirit does not recognize itself,
      being as different from what it was as is the white butterfly from the
      repulsive caterpillar. It does not know how it can have merited so great a
      good, or rather, whence this grace came178  which it well knows it merits not. The soul
      desires to praise our Lord God and longs to sacrifice itself and die a thousand
      deaths for Him. It feels an unconquerable desire for great 133crosses
      and would like to perform the most severe penances; it sighs for solitude and
      would have all men know God, while it is bitterly grieved at seeing them offend
      Him. These matters will be described more fully in the next mansion; there they
      are of the same nature, yet in a more advanced state the effects are far
      stronger, because, as I told you, if; after the soul has received these
      favours, it strives to make still farther progress, it will experience great
      things. Oh, to see the restlessness of this charming little butterfly, although
      never in its life has it been more tranquil and at peace! May God be praised!
      It knows not where to stay nor take its rest; everything on earth disgusts it
      after what it has experienced, particularly when God has often given it this
      wine which leaves fresh graces behind it at every draught.
    
   
7.
      It despises the work it did while yet a caterpillar—the slow weaving of its
      cocoon thread by thread—its wings have grown and it can fly; could it be
      content to crawl? All that it can do for God seems nothing to the soul compared
      with its desire. It no longer wonders at what the saints bore for Him, knowing
      by experience how our Lord aids and transforms the soul until it no longer
      seems the same in character and appearance. Formerly it feared penance, now it
      is strong: it wanted courage to forsake relations, friends, or possessions:
      neither its actions, its resolutions, nor separation from those it loved could
      detach the soul, but rather seemed to increase its fondness. Now it finds even
      their rightful claims a burden,179  fearing contact with 134them
      lest it should offend God. It wearies of everything, realizing that no true
      rest can be found in creatures.
    
   
8.
      I seem to have enlarged on this subject, yet far more might be said about it;
      those who have received this favour will think I have treated it too briefly.
      No wonder this pretty butterfly, estranged from earthly things, seeks repose
      elsewhere. Where can the poor little creature go? It cannot return to whence it
      came, for as I told you, that is not in the soul’s power, do what it will, but
      depends upon God’s pleasure. Alas, what fresh trials begin to afflict the mind!
      Who would expect this after such a sublime grace?180  In fact in one way or another we must carry
      the cross all our lives. If people told me that ever since attaining to the
      prayer of union they had enjoyed constant peace and consolation, I should reply
      that they could never have reached that state, but that, at the most, if they
      had arrived as far as the last mansion, their emotion must have been some
      spiritual satisfaction joined to physical debility. It might even have been a
      false sweetness caused by the devil, who gives peace for a time only to wage
      far fiercer war later on. I do not mean that those who reach this stage possess
      no peace; they do so in a very high degree, for their sorrows, though extremely
      severe, are so beneficial and proceed from so good a source as to procure both
      peace and happiness.
    
   
9.
      Discontent with this world gives such a painful longing to quit it that, if the
      heart finds comfort, 135it
      is solely from the thought that God wishes it to remain here in banishment.
      Even this is not enough to reconcile it to fate, for after all the gifts
      received, it is not yet so entirely surrendered to the will of God as it
      afterwards becomes. Here, although conformed to His will, the soul feels an
      unconquerable reluctance to submit, for our Lord has not given it higher grace.
      During prayer this grief breaks forth in floods of tears, probably from the
      great pain felt at seeing God offended and at thinking how many souls, both
      heretics and heathens, are lost eternally, and keenest grief of all, Christians
      also! The soul realizes the greatness of God’s mercy and knows that however
      wicked men are, they may still repent and be saved; yet it fears that many
      precipitate themselves into hell.
   
   
10.
      Oh, infinite greatness of God! A few years ago—indeed, perhaps but a few
      days—this soul thought of nothing but itself. Who has made it feel such
      tormenting cares? If we tried for many years to obtain such sorrow by means of
      meditation, we could not succeed.
   
   
11.
      God help me! If for long days and years I considered how great a wrong it is
      that God should be offended, and that lost souls are His children and my
      brethren; if I pondered over the dangers of this world and how blessed it would
      be to leave this wretched life, would not that suffice? No, daughters, the pain
      would not be the same. for this, by the help of God, we can obtain by such
      meditation; but it does not seem to penetrate the very depths of our being like
      the other which 136appears
      to cut the soul to pieces and grind it to powder through no action—even
      sometimes with no wish—of its own. What is this sorrow, then? Whence does it
      come? I will tell you. Have you not heard (I quoted the words to you just now,
      but did not apply to them this meaning)181  how the Bride says that God ‘brought her into
      the cellar of wine and set in order charity in her’?182  This is what happens here. The soul has so
      entirely yielded itself into His hands and is so subdued by love for Him that
      it knows or cares for nothing but that God should dispose of it according to
      His will. I believe that He only bestows this grace on those He takes entirely
      for His own. He desires that, without knowing how, the spirit should come forth
      stamped with His seal for indeed it does no more than does the wax when
      impressed with the signet. It does not mould itself but need only be in a fit
      condition—soft and pliable; even then it does not soften itself but must
      merely remain still and submit to the impression.
    
   
12.
      How good Thou art, O God! All is done for us by Thee, Who dost but ask us to
      give our wills to Thee that we may be plastic as wax in Thy hands. You see,
      sisters, what God does to this soul so that it may know that it is His. He
      gives it something of His own—that which His Son possessed when living on
      earth—He could bestow on greater gift on us. Who could ever have longed more
      eagerly to leave this life than did Christ? 137 As He said at the Last Supper: ‘With
      desire have I desired’183  this. O Lord! does not that bitter death Thou
      art to undergo present itself before Thine eyes in all its pain and horror?
      ’No, for My ardent love and My desire to save souls are immeasurably stronger
      than the torments. This deeper sorrow I have suffered and still suffer while
      living here on earth, makes other pain seem as nothing in comparison.’
    
   
13.
      I have often meditated on this and I know that the torture a friend of mine184  has felt, and still feels, at seeing our Lord
      sinned against is so unbearable that she would far rather die than continue in
      such anguish. Then I thought that if a soul whose charity is so weak compared
      to that of Christ—indeed, in comparison with His this charity might be said
      not to exist—experiences this insufferable grief, what must have been the feelings
      of our Lord Jesus Christ and what must His life have been? for all things were
      present before His eyes and He was the constant witness of the great offences
      committed against His Father. I believe without doubt that this pained Him far
      more than His most sacred Passion. There, at least, He found the end of all His
      trials, while His agony was allayed by the consolation of gaining our salvation
      through His death and of proving how He loved His Father by suffering for Him.
      Thus, people who, urged by fervent love, perform great penances 138hardly
      feel them but want to do still more and count even that as little. What, then,
      must His Majesty have felt at thus publicly manifesting His perfect obedience
      to His Father and His love for His brethren? What joy to suffer in doing God’s
      will! Yet I think the constant sight of the many sins committed against God and
      of the numberless souls on their way to hell must have caused Him such anguish
      that, had He not been more than man, one day of such torment would have
      destroyed not only His life but many more lives, had they been His.