If writing is exhausting, then reading is scattering

"But reading and writing must not be dissociated; one ought to “have alternate recourse” to those two pursuits and “blend one with the other.” If too much writing is exhausting (Seneca is thinking of the demands of style), excessive reading has a scattering effect: “In reading of many books is distraction.” By going constantly from book to book, without ever stopping, without returning to the hive now and then with one's supply of nectar —hence without taking notes or constituting a treasure store of reading— one is liable to retain nothing, to spread oneself across different thoughts, and to forget oneself. "

http://foucault.info/documents/foucault.hypomnemata.en.html

Foucault, Michel. "Self Writing." In Dits et écrits, pp. 415-430. Vol. IV., 1983.