In this short review, I revise the notion of gnostic cells posited by Konorski, together with similar arguments by James, Lettvin and Barlow--namely, the idea of pontifical, grandmother and cardinal cells, respectively. I then discuss whether the characteristics of the recently discovered concept cells, i.e. neurons in the human medial temporal lobe with a very high degree of specificity and invariance, fit the conjecture of gnostic or grandmother cells and then discuss the key role of concept cells in memory formation.