Disuse Quotes (2 quotes)
Just as iron rusts from disuse and stagnant water putrefies, or when cold turns to ice, so our intellect wastes unless it is kept in use.
C.A. 289 v. c. In Irma A. Richter and Thereza Wells (eds.), Leonardo da Vinci: Notebooks (1952, 1980), 245. Also translated as Iron rusts from disuse; stagnant water loses its purity and in cold weather becomes frozen; even so does inaction sap the vigour of the mind, in Edward McCurdy, The Notebooks of Leonardo Da Vinci (1939), Vol. 1, 89. Translated as Just as iron rusts unless it is used, and water putrifies or, in cold, turns to ice, so our intellect spoils unless it is kept in use, in Jean Paul Richter (trans.), The Notebooks of Leonardo Da Vinci (1888), Note 1177.
Organs, faculties, powers, capacities, or whatever else we call them; grow by use and diminish from disuse, it is inferred that they will continue to do so. And if this inference is unquestionable, then is the one above deduced from itthat humanity must in the end become completely adapted to its conditionsunquestionable also. Progress, therefore, is not an accident, but a necessity.
Social Statics: Or, The Conditions Essential to Human Happiness Specified, and the First of them Developed (1851), 65.