Otherwise he would collapse inwards upon the great dark void

“…life was a hollow shell all round him, roaring and clattering like the sound of the sea, a noise in which he participated externally, and inside this hollow shell was all the darkness and fearful space of death … otherwise he would collapse inwards upon the great dark void which circled at the centre of his soul … Something must come with him into the hollow void of death in his soul, fill it up, and so equalise the pressure within to the pressure without. For day by day he felt more and more like a bubble filled with darkness, round which whirled the iridescence of his consciousness, and upon which the pressure of the outer world, the outer life, roared vastly.”

Women in Love, D. H. Lawrence.