This salutary crisis is a purgatory before death, in which the soul is purified under the influence, not of a sensible fire, but of the spiritual fire of contemplation and love. "And thus," says St: John of the Cross, "the soul which passes through this state in the present life, and is perfectly purified, either enters not into purgatory, or is detained there but a moment, for one hour here is of greater moment than many there." (14) The reason is that on earth man is purified while meriting and growing greatly at times in charity, whereas after death he is purified without meriting. And as purgatory is a penalty and every penalty presupposes a sin that could have been avoided, the normal way of sanctity is to undergo the passive purifications of which we are speaking before death and not after death. In reality, however, rare are they who go immediately from earth to heaven, without passing through purgatory. The true order of Christian life is fully realized only in the saints.
Summary from Garrigou-Lagrange