Tolstoy and the White Bear

Greatly enjoying M.J. Hyland's two novels at the moment (have finished How the Light Gets In and am half-way through Carry Me Down). The narrator of How the Light Gets In mentions how it is forbidden to think of the Torah when you’re on the toilet. As a child, she goes on, Tolstoy was tormented by his brother who told him to go stand in the corner and not think about a white bear. As you’d expect, the white bear was all he could think of.

A perplexing state of affairs. Do not think of these words, these words you are reading. Anything else but these words: I forbid it.