From "Star Trek: Dagger of the Mind (#1.9)"
What did he do to us?
Dr. Simon van Gelder
He can reshape any mind he chooses. He used it to erase our memories, put his own thoughts there. He was surprised it took so much power. We fought him, remember? But we grew so tired. Our minds so blank, so open, that any thought he placed there became our thoughts. Our minds so empty, like a sponge needing thoughts, begging, empty. Loneliness. So lonely to be sitting there empty, wanting any word from him.