Solution
All the numbers are prime numbers starting with A=2, B=3, C=5, D=7, .......... Y=97, Z=101.
Therefore, the message is a saying by Henry Ford:
ANYONE WHO STOPS LEARNING IS OLD WHETHER AT TWENTY OR EIGHTY. ANYONE WHO KEEPS LEARNING STAYS YOUNG.
THE GREATEST THING IN LIFE IS TO KEEP YOUR MIND YOUNG.