Definition of "conscience"

Never do anything against conscience, even if the state demands it.

1949, Albert Einstein, as quoted by Virgil Henshaw in Albert Einstein: Philosopher Scientist

As for Grierson, he poured liquor into himself as if it were so much soothing syrup, demonstrating that a good digestion is the highest form of good conscience.

1938, Norman Lindsay, Age of Consent, 1st Australian edition, Sydney, N.S.W.: Ure Smith, published 1962, page 159

[“]Twer is not a friend of mine testifying against me reluctantly and for conscience’ sake, as the prosecution would have you believe. He is a spy, performing his paid job.[”]

1951, Isaac Asimov, Foundation, Panther Books Ltd, published 1974, part V: The Merchant Princes, chapter 14, page 175

‘Then the father has a great fight with his terrible conscience,’ said Munday with granite seriousness. ‘Should he make a row with the police […]? Or should he say nothing about it and condone brutality for fear of appearing in the newspapers?

1963, Margery Allingham, chapter 18, in The China Governess‎

Thus conscience does make cowards of us all;And thus the native hue of resolutionIs sicklied o'er with the pale cast of thought.

c. 1599–1602 (date written), William Shakespeare, “The Tragedie of Hamlet, Prince of Denmarke”, in Mr. William Shakespeares Comedies, Histories, & Tragedies […] (First Folio), London: […] Isaac Iaggard, and Ed[ward] Blount, published 1623, [Act III, scene i]