Solitude from words is not solitude from communication. The soul that, in consequence of its sanctification, does not speak outward to things that are temporal, speaks inward to things that are eternal. And in proportion as it ceases from those communications with men which God does not call for and does not authorize, it increases its communications with God himself.
And these last remarks indicate the true result of spiritual solitude, when it is rightly understood and experienced. The soul is not left alone with itself,— which would be much the same as to say, that it is left alone with Satan, — but is left alone with God, who is Eternal Life. Separation, in its spiritual application, is not only seclusion, but transition. Separation from the world, when predicated of a being to whom absolute separation is an impossibility, is transition to God; and he who is not of the world, is of God; alone and in unison at the same time; in solitude from that which is evil, but in union with that which is good. He has hidden himself, not in the dark and weak enclosure which selfishness furnishes to those who do not believe, but in the strong fortress of the Infinite. He is not only with God, but in him; not only in harmony of action, but in the sacred enclosure of his being: — so that God may be said, in the language of Scripture, to “compass him round about." No noise of unholy thoughts, no suggestions of unhallowed reason, no clamors of unsatisfied desire, no confusion of the tongues of men, nothing that is hurtful, nothing that is unprofitable, reaches him. "As the mountains are round about Jerusalem, so the Lord is round about his people." Ps. 125:2.
— edited from A Treatise on Divine Union (1851) Part 6, Chapter 10.