Energies and perseverances

Thomas Jefferson to Dr. John P. Emmet, May 2, 1826, discovered in Nathaniel Grossman, The Sheer Joy of Celestial Mechanics:

[…] consider that we do not expect our schools to turn out their alumni already on the pinnacles of their respective sciences; but only so far advanced in each as to be able to pursue them by themselves, and to become Newtons and Laplaces by energies and perseverances to be continued throughout life.