According to his early biographers, at a certain point in his life Kant had a ‘maxim’ not to smoke more than a single pipe a day, tempted though he was. He adhered to this maxim rigorously. After a while, however, he bought a bigger pipe.

Jens Timmermann, ‘Kant’s Puzzling Ethics of Maxims’, The Harvard Review of Philosophy, vol. 8 (2000), p. 39