In a letter to his daughter Martha, written in March,1787, Jefferson writes:

"Of all the cankers of human happiness, none corrodes with so silent, yet baneful a tooth, as indolence.

"Body and mind both unemployed, our being becomes a burthen, and every object about us loathsome, even the dearest.

"Idleness begets ennui, ennui the hypochondria, and that a diseased body.

"No laborious person was ever yet hysterical.

"Exercise and application produce order in our affairs, health of body and cheerfulness of mind. These make us precious to our friends.

"It is while we are young that the habit of industry is formed. If not then, it never is afterwards.

"The future of our lives, therefore, depends on employing well the short period of youth.

"If at any moment, my dear, you catch yourself in idleness, start from it as you would the precipice of a gulf.

"You are not, however, to consider yourself as unemployed while taking exercise. That is necessary for your health, and health is the first of all objects."