Russian psychiatrist Vasily Kasatkin devoted more than half a century to collecting and studying dreams and is the author of the book "Theory of Dreams" (Medical 1967). The theory Kasatkin proposes is not filled with mystical symbols, but numerous scientifically-based facts and interesting observations. His work is based on an extensive 30-year collection of dreams, which allowed Kasatkin to make significant conclusions. He demonstrates that the sleeping brain warns us of impending disease, of which the first symptoms may occur weeks, months or even years before the overt physical symptoms.