Grisey's écriture classes at the Conservatoire National Supérieur were a constant in his student years. Several exercise books from that time remain: Grisey practiced figured bass accompaniment, counterpoint, harmony, and orchestration in notebooks that ran into the hundreds of pages. In a later interview, Grisey complained of this education, at once boring and difficult and destined to produce a generation of traditionalist-copycat composers:

Still, Grisey was a proficient and motivated student, and successfully mastered the requirements of the Conservatoire. He received first prizes in history of music (1966), harmony (1967), fugue and counterpoint (1968), and second prize in piano accompaniment (1970). The latter was especially impressive considering the piano wasn't his first instrument.

The only letters Grisey wrote between 1968 and 1970 were again during his breaks in Belfort. These letters were typical of the composer's youth: he avoided the prosaic in favor of the abstractly spiritual. On February 17, 1968, Grisey meditated on death in a letter to Jocelyne Simon, returning to a theme of his teenage years. “Death, too, so close and so far …” he wrote:

On April 10, from Belfort again, Grisey told Simon that he was reading Blaise Pascal's Pensées. The book contains much that appears relevant to Grisey's aesthetic. For Pascal, human nature was at its core a process of constant change, an idea that fits neatly into Grisey's later goal to write music of a “pure sonic becoming, mutating ceaselessly.” A famous passage in Pascal also parallels Grisey's later idea of the different planes on which his music operated, from the microscopic to the cosmic. “What is a man in the infinite?” Pascal wrote.