Coffee into theorems
The late mathematician P. Erdös has often been associated with the
observation that "a mathematician is a machine for converting coffee
into theorems" (e.g., Hoffman 1998, p. 7). However, this
characterization appears to be due to his friend, Alfred Rényi
(MacTutor, Malkevitch). This thought was developed further by Erdös'
friend and Hungarian mathematician Paul Turán), who suggested that
weak coffee was suitable "only for lemmas" (MacTutor, Malkevitch).
From http://mathworld.wolfram.com/Theorem.html
From http://mathworld.wolfram.com/Theorem.html