We can conceive a thinking being to have either many or few perceptions. Suppose the mind to be reduced even below the life of anoyster. Suppose it to have only one perception, as of thirst or hunger. Consider it in that situation. Do you conceive any thing but merely that perception? Have you any notion of self or substance? If not, the addition of other perceptions can never give you that notion.

The Philosophy of David Hume (ed. 1963)