The four good characteristics of a good memory: (1) If you read once a passage and if you can reproduce the same nicely, it is a sign to indicate that you have a very good memory. (2) If you can reproduce the same thing without increase or decrease, addition or subtraction. (3) If you can preserve a fact or passage or anything for a very considerable period (retentive memory). (4) If you can reproduce a passage at once without any difficulty when it is needed.
But mine is somewhere between 1 and 2. 😦
It would be great if our memory had all the 4. 🙂