The inspiration which led Descartes to his reform of traditional mathematical thought took place soon after his encounter in the autumn of 1618 with Isaac Beeckman, a Dutch scholar his senior by eight years. The significance of this meeting for him is shown clearly in his letter of April 23, 1619 to Beeckman: "You are truly the only one who awoke [me] from sloth, recalled erudition which had almost passed away from memory, and bettered my mind which was drifting away from serious occupations."¹