The polymath Mary Somerville was a prominent figure in mathematical and scientific circles across Europe for roughly half a century. (In particular, she produced the first translation of Laplace’s Mécanique Céleste into English, and was one of the first people to suggest the possibility of finding new planets by studying orbital perturbations.) In the last chapter of her Personal Recollections there’s a fine tribute to the way that learning retains its value to the very end of one’s life.
I am now in my 92nd year… I am extremely deaf, and my memory of ordinary events, and especially of the names of people, is failing, but not for mathematical and scientific subjects. I am still able to read books on the higher algebra for four or five hours in the morning, and even to solve the problems. Sometimes I find them difficult, but my old obstinacy remains, for if I do not succeed to-day, I attack them again on the morrow.
It’s a variety of “obstinacy” that many of us who are much younger would love to emulate.