The Dark Night of the SoulChapter XXII. Explains the third line of the second stanza

Happiness of the soul in having overcome its enemies.
O happy lot!

It is very evident that it was a blessed thing for the soul to have succeeded in such an enterprise as this, by which it was delivered out of the hands of satan, from the world, and from its own sensuality, in which, having gained that liberty of spirit so precious and desirable, it rose from meanness to dignity, from being earthly and human being heavenly and divine, having its ‘conversation in Heaven,’ ' like unto those who are in a state of perfection, as I shall proceed to explain.

2. I shall, however, be brief, because the most important point—that which chiefly determined me to explain this dark night to many souls who enter on it without knowing it, as I said in the preface—has been already in some degree explained, and I have also shown, though not in adequate terms, how great are the blessings that descend upon the soul in this night, and what a great happiness it is to be passing through it. This I did that when such souls are alarmed at the trials that have come upon them, they may be encouraged by the certain hope of the numerous and great blessings of God which they receive in this night. Besides this, it was a happy lot for the soul for the reason assigned in the following line,

1 Phil, iii, 20.