I am like a slave who, enjoying an imaginary liberty during sleep, begins to suspect that his liberty is only a dream; he fears to wake up and conspires with his pleasant illusions to retain them longer. So insensibly to myself I fall into my former opinions; and am slow to wake up from this slumber for fear that the labors of waking life which will have to follow the tranquility of this sleep, instead of leading me into the daylight of the knowledge of truth, will be insufficient to dispell the darkness of all the difficulties which have just been raised.

- René Descartes from Meditations on the First Philosophy