He has few memories of his past, and he almost never thinks about it, although his memory for other things is very good. He attributes this to his inability to form mental images. Although he recognizes familiar things when he sees them, he cannot call up images of them afterward in his head: he cannot visualize even so simple an image as a flag; he cannot, when he is away, recall his wife’s face. (This condition is rare but not unheard of; it has been proposed that it is more common in people who think in abstractions.)



[…]



When he was in America, he was compelled to procure his own food. Because he didn’t want to waste time on choice or preparation, he developed rigid routines that he could follow without thinking. For years, according to a colleague, he made the same meal every morning for breakfast, which he conceived of as a recipe for maximum health: sausage links, green peppers, yogurt, and a banana, all in one bowl. One day, the colleague’s nutritionist wife explained to him that this was not a particularly healthy meal, and suggested a better meal; the next day he switched to the new meal and never varied it.

How to be Good. A profile of philosopher Derek Parfit.