It seems that Keynes was the one who first _insisted_ on having Y for Yncome. I believe he put it that way in one of his earlier manuscripts. = He uses this notation through all of the _General Theory_. Right now I have only Vol XIV of Keynes' Collected Writings with me. There (JMK, CW, XIV, p.80) Keynes writes to Hicks (in response to his SILL-article which = intends to render the essence of the General Theory): "On one point of detail, I regret that you use the symbol _I_ for income. ... after trying both, I believe it is easier to use _Y_ for income and _I_ for investment. = Anyhow we ought to try and keep uniform in usage." There you have _Y_ as notational programme. To this Hicks was to reply = (JMK, CW, p.81): "I am sorry about using _I_ for income. ... I hadn't the ghost of an = idea ... that there was any particular sanctity about _Y_, and that it hadn't just been drawn out of a hat." Therefore I conclude that it was Keynes' _General Theory_ which started = the convention of Y =3D income. Michael Ambrosi