Rene Descartes

René Descartes (1596-1650)

Portrait by Frans Hals

There was a young student called Fred,
Who was questioned on Descartes and said:
    "It's perfectly clear
    That I'm not really here,
For I haven't a thought in my head."
    —V. R. Ormerod

Dr Johnson, when sober or pissed,
Could be frequently heard to insist,
    Letting out a great fart:
    "Yes, I follow Descartes—
I stink, and I therefore exist."
    —A. Cinna