  Though Reid uses the term ‘acquaintance,’ the things retained through memory are things previously perceived or experienced. The term ‘acquaintance’ has acquired a technical sense that it did not have in Reid’s day, so it is better to see Reid as holding that memory preserves contact with events previously apprehended through perception and thereby known by acquaintance. Acquaintance presupposes apprehension, and prior episodes of apprehension are necessary for retained acquaintance.