Abstract: I have always thought that the most sacred duty of men was to give their children an education that prevented them at a more advanced age from regretting their youth, the only time when one can truly gain instruction. You are, my dear son, in this happy age when the mind begins to think, and when the heart has passions not yet lively enough to disturb it.
Now is perhaps the only time of your life that you will devote to the study of nature. Soon the passions and pleasures of your age will occupy all your moments; and when this youthful enthusiasm has passed, and you have paid to the intoxication of the world the tribute of your age and rank, ambition will take possession of your soul; and even if in this more advanced age, which often is not any more mature, you wanted to apply yourself to the study of the true Sciences, your mind then no longer having the flexibility characteristic of its best years, it would be necessary for you to purchase with painful study what you can learn today with extreme facility. So, I want you to make the most of the dawn of your reason; I want to try to protect you from the ignorance that is still only too common among those of your rank, and which is one more fault, and one less merit.
You must early on accustom your mind to think, and to be self-sufficient. You will perceive at all the times in your life what resources and what consolations one finds in study, and you will see that it can even furnish pleasure and delight.