। ॥ १५२ ॥
In plain words
Stay long in the experience of the Self, and the mind takes on the very form of the Self — the way a river that has reached the ocean becomes, utterly, the sea.
Close to the Sanskrit
From the experience of the Self, held for a very long time, the mind becomes of the form of the Self — as a river that has gone to the ocean attains, utterly, the state of being the sea.