“One thing I have frequently observed in children, that when they have got possession of any poor creature, they are apt to use it ill: they often torment, and treat it very roughly, young birds, butterflies, and such other poor animals which fall into their hands, and that with a seeming kind of pleasure. This I think should be watched in them, and if they incline to any such cruelty, they should be taught the contrary usage. For the custom of tormenting and killing of beasts, will, by degrees, harden their minds even towards men; and they will delight in the suffering and destruction of inferior creatures, will not be apt to be very compassionate or benign to those of their own kind. Our practice takes notice of this in the exclusion of butchers from juries of life and death.”
Sec. 116
Some Thoughts Concerning Education (1693)
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John Locke 144
English philosopher and physician 1632–1704Related quotes

Book VIII 1337b.5 http://books.google.com/books?id=ZrDWAAAAMAAJ&pg=PA245&dq=%22absorb+and+degrade+the+mind%22&hl=en&sa=X&ei=c6NaUbatEYWp4AOWp4CoBA&ved=0CHYQ6AEwDA#v=onepage&q=%22absorb%20and%20degrade%20the%20mind%22&f=false, 1885 edition
Politics
Context: There can be no doubt that children should be taught those useful things which are really necessary, but not all things, for occupations are divided into liberal and illiberal; and to young children should be imparted only such kinds of knowledge as will be useful to them without vulgarizing them. And any occupation, art, or science which makes the body, or soul, or mind of the freeman less fit for the practice or exercise of virtue is vulgar; wherefore we call those arts vulgar which tend to deform the body, and likewise all paid employments, for they absorb and degrade the mind. There are also some liberal arts quite proper for a freeman to acquire, but only in a certain degree, and if he attend to them too closely, in order to attain perfection in them, the same evil effects will follow.

2, 22, 1
On Abstinence from Killing Animals

Parochial and Plain Sermons, London, 1868; quoted in Matthew Scully, [//books.google.it/books?id=SYY7AAAAQBAJ&pg=PT30 Dominion] (2002).

Meet the Press NBC, 12 June 2016
2010s, 2016

19th World Vegetarian Congress 1967

Alberuni, I, pp.19-20. quoted from K.S. Lal, Indian Muslims who are they, 1990
From Alberuni's India

“The old often envy the young; when they do, they are apt to treat them cruelly.”
1920s, What I Believe (1925)

My Life (1927), chapter 28; Liveright Publishing, 2013, p. 276 https://books.google.it/books?id=7bmj03oQH9IC&pg=PA276.