difference, one of Derrida’s key terms, as early as the mid-
1890 s. Yet Freud, alas, is not a Derridean. Derrida remarks that
all Freudian concepts, “without exception, belong to the his-
tory of metaphysics” ( 197 ). He wants to claim Freud as support
for his theory, to make him a champion of difference, yet at the
same time he is reluctant to grant Freud the status of an en-
lightened champion of deconstruction. Freud must remain a
mystified metaphysician, so that Derrida can unmask him: his
blindness enables Derrida’s insight.
Leaving the Project for a Scientific Psychology,Derrida
shifts to a second text by Freud. In Freud’s brief, intriguing
“Note Upon the Mystic Writing Pad,” composed three decades
after the Project(in 1925 ), Freud relies on the metaphor of writ-
ing in order to describe the workings of perception and mem-
ory. The mystic writing pad, marketed as a novelty, consists of
a wax tablet covered by a sheet of wax paper and, on top of the
paper, a celluloid sheet. One writes on the celluloid sheet and
then erases the writing by pulling apart the layers of the writ-
ing pad, so that the pad can be used afresh. The traces of what
one has written are, however, retained on the wax tablet. Freud
remarks that the celluloid sheet resembles conscious percep-
tion, which is continually fresh, and the wax tablet uncon-
scious memory, full of traces of the past.
Derrida argues that Freud turns to the mystic writing
pad in order to solve the original dilemma of the Project:the
difference between perception and memory. The Projectar-
gued that some neurons are permeable (capable of receiving
and retaining impressions, so that they become agents of
memory) while others are impermeable (the agents of percep-
tion, rather than memory). The difference between memory
neurons and perception neurons, Derrida points out, is like
the difference between a sheet of paper (which conserves its
Writing and DifferenceandOf Grammatology 107