'For a sign and for a memorial,' denotes that a thing should be perpetually remembered.

(Notae: Arcana Coelestia 8066)

8066. 'And it shall be for you as a sign on your hand' means that it shall be constantly in their will. This is clear from the meaning of 'a sign' as constant recollection (for an object serving as a sign or one serving as a memorial acts as a constant reminder; and the purpose of 'a sign on the hand' was that every time they moved their hand or did anything they would be reminded of it, and the purpose of 'a memorial between the eyes' was that every time they looked at something they would be reminded of it); and from the meaning of 'hand' as power, dealt with in 878, 3387, 4931-4937, 5327, 5328, 5544, 6292, 6947, 7011, 7188, 7189, 7518, 7673, here as the will because every action and the power of action exercised by the hand comes from the will.