Meditations - pg. 65

I will suppose, then, not that there is a supremely good God, the source of truth; but that there is an evil spirit, who is supremely powerful and intelligent, and does his utmost to deceive me. I will suppose that sky, air, earth, colours, shapes, sounds and all external objects are mere delusive dreams, by means of which he lays snares for my credulity. I will consider myself as having no hands, no eyes, no flesh, no blood, no senses, but just having a false belief that I have all these things. I will remain firmly fixed in this meditation, and resolutely take care that, so far as in me lies, even if it is not my power to know some truth, I may not assent to falsehood nor let myself be imposed upon by that deceiver, however powerful and intelligent he may be. But this plan is irksome, and sloth brings me back to ordinary life. I am like a prisoner who happens to enjoy an imaginary freedom during sleep, and then begins to suspect he is asleep; he is afraid to wake up, and connives at the agreeable illusion.