Shakespeare on Habit Formation and Addiction

How use doth breed a habit in a man!

(Two Gentlemen of Verona, Act 5, Scene 4, Line 2149; a variation of this quotation introduces  “A Theory of Rational Addiction,” by Gary S. Becker and Kevin M. Murphy, Journal of Political Economy Vol. 96, No. 4 (Aug., 1988), pp. 675-700).

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Good night- but go not to my uncle's bed.

Assume a virtue, if you have it not.

That monster, custom, who all sense doth eat

Of habits evil, is angel yet in this,

That to the use of actions fair and good

He likewise gives a frock or livery,

That aptly is put on. Refrain to-night,

And that shall lend a kind of easiness

To the next abstinence; the next more easy;

For use almost can change the stamp of nature…

(Hamlet, Act 3, Scene 4, Lines 2562-2571)