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."