Verse 20

In plain words

The fourth is to be poured like oil into the three. Since this is so, the yogin must be attentive in every state, so that the nature of pure knowledge, even once gained by the methods described, does not perish. So he says: Into the three states, waking and the rest, the fourth, the abode whose form is the light of pure knowledge and whose essence is the savour of the bliss of the fourth, is to be poured like oil: as oil, spreading gradually more and more, pervades what holds it, so is it to be poured. In all three states, by the savour of the fourth that shines at their beginning and end points, whose nature is their opening and their subsiding, let him pervade the middle condition too, by the method of firm hold, so that he attains oneness with it. By "In waking, dream and deep sleep, the fullness of the fourth arises", the mere presence of the fourth was declared, in the states of waking and the rest as they spread forth of their own accord, for one who has the firm hold of attention to the upsurge and to the wheel of powers. By "The enjoyer of the three is the lord of heroes", the withdrawal of waking and the rest was shown, by the method of forceful digestion suited to the śāmbhava upāya. By this sūtra, though, it is said that the three, waking and the rest, which are like petals, are to be steeped in the savour of the fourth, by the method of firm hold suited to the āṇava upāya. That is the difference.