Enjoy the blessing of strength while you have it and do not bewail it when it is gone, unless, forsooth, you believe that youth must lament the loss of infancy, or early manhood the passing of youth. Life's race-course is fixed; Nature has only a single path and that path is run but once, and to each stage of existence has been allotted its own appropriate quality; so that the weakness of childhood, the impetuosity of youth, the seriousness of middle life, the maturity of old age.. each bears some of Nature's fruit, which must be garnered in its own season.
Marcus Tullius CiceroLet art, then, imitate nature, find what she desires, and follow as she directs. For in invention nature is never last, education never first; rather the beginnings of things arise from natural talent, and ends are reached by discipline.
Marcus Tullius Cicero