What can be full and still hold more?
Answer: Your mind.
Your mind can be full of ideas, memories, knowledge, and experiences, yet you can still learn something new.
The riddle works because “full” usually suggests that there is no room left for anything else. That makes us think of cups, boxes, bags, or other physical containers.
But the mind does not work like a simple container with a fixed visible limit. Even when someone feels full of information, they can continue to learn, remember, and understand more.
That is why your mind is a fitting answer to the clue.
