“The Expelled’ (1945) :
Memories are killing. So you must not think of certain things, of those that are dear
to you, or rather you must think of them, for if you don’t there is the danger of
finding them, in your mind, little by little. That is to say, must think of them for a
while, a good while, every day several times a day, until they sink forever in the
mud. That’s an order.

Beckett knows, of course, that nothing is “forever,” and that he can hardly
obey his own order to put the matter behind him. “Little by little,” those
“killing” memories return.