One of the licentiate's philosophical meditations: "[I start] to think about my own thoughts of the situation in which I find myself. I even think that I think of them, and divide myself into an infinite retrogressive sequence of I's who consider each other. I do not know which I to stop at as the actual, and in the moment I stop at one, there is indeed again an I which stops at it. I become confused and feel a dizziness as if I were looking down into a bottomless abyss."
And another: "You see, my friend, a movement presupposes a direction. The mind cannot proceed without moving along a certain line; but before following this line, it must already have thought it. Therefore one has already thought every though before one thinks it. Thus every thought, which seems the work of a minute, presupposes an eternity. This could drive me almost to madness."