What is the meaning of [One is never too old to learn]

However much you know, there is always more to learn, and whatever your age,
you can still increase your knowledge. Cicero refers to ‘a zeal of learning,
which, in the case of wise and well-trained men, advances in every pace with
age’. The favourite saying of Michelangelo, the great Italian sculptor and
painter, was: ‘I am learning.’