From Farm House to the White House by William M. Thayer

"You are now extending into that stage of life when good or bad habits are formed; when the mind will be turned to things useful and praiseworthy or to dissipation and vice. Fix on which ever it may, it will stick by you; for you know it has been said, and truly, 'The way the twig is bent the tree's inclined.' This, in a strong point of view, shows the propriety of letting your inexperience be directed by maturer advice, and in placing guard upon the avenues which lead to idleness and vice.

The latter will approach like a thief, working upon your passions, encouraged, perhaps, by bad examples, the propensity to which will increase in proportion to the practice of it and your yielding.

Virtue and vice cannot be allied, nor can idleness and industry; of course if you resolve to adhere to the former of these extremes, an intimacy with those who incline to the latter of them would be extremely embarrassing to you; it would be a stumbling block in your way, and act like a mill-stone hung to your neck; for it is the nature of idleness and vice to obtain as many votaries as they can....