“It is a hyperbole excusable in poetic language, but not scientifically valid, when he [Jesus] is identified with the ideal of humanity. The ideal is the unconditioned, the absolute, but every phenomenon in time and space is conditioned and limited, and cannot therefore coincide with the ideal. This hyperbole of pious faith may grow out of noble feelings, but for all that it remains essentially false, and is harmful when seriously regarded as dogma.”

The Evolution of Physics (1938) (co-written with Leopold Infeld) <!-- later published by Simon & Schuster (1967) -->
1930s
Context: Physical concepts are free creations of the human mind, and are not, however it may seem, uniquely determined by the external world. In our endeavor to understand reality we are somewhat like a man trying to understand the mechanism of a closed watch. He sees the face and the moving hands, even hears its ticking, but he has no way of opening the case. If he is ingenious he may form some picture of a mechanism which could be responsible for all the things he observes, but he may never be quite sure his picture is the only one which could explain his observations. He will never be able to compare his picture with the real mechanism and he cannot even imagine the possibility or the meaning of such a comparison. But he certainly believes that, as his knowledge increases, his picture of reality will become simpler and simpler and will explain a wider and wider range of his sensuous impressions. He may also believe in the existence of the ideal limit of knowledge and that it is approached by the human mind. He may call this ideal limit the objective truth.

"December 11 : Wind", p. 152
A Year in the Maine Woods (1995)

Unsourced

Source: The New Ethics (1907), Silent Martyrs of Civilization, p. 65

The Levinas reader by Levinas, Emmanuel p. 89

Variant translations:
Blessed is he who carries within himself a God, an ideal, and who obeys it: ideal of art, ideal of science, ideal of the gospel virtues, therein lie the springs of great thoughts and great actions; they all reflect light from the Infinite. (As quoted by Sir William Osler in his introduction to The Life of Pasteur (1907) by Rene Vallery-Radot, as translated by R .L. Devonshire (1923)
Blessed is he who carries within himself a god and an ideal and who obeys it — an ideal of art, of science, or gospel virtues. Therein lie the springs of great thoughts and great actions; they all reflect light from the Infinite. (As quoted in The Wordsworth Dictionary of Quotations (1998) by Connie Robertson, p. 320)
Discours de réception de Louis Pasteur (1882)
Original: (fr) La grandeur des actions humaines se mesure à l’inspiration qui les fait naître. Heureux celui qui porte en soi un Dieu, un idéal de la beauté et qui lui obéit : idéal de l’art, idéal de la science, idéal de la patrie, idéal des vertus de l’Évangile! Ce sont là les sources vives des grandes pensées et des grandes actions. Toutes s’éclairent des reflets de l’infini.

Reported in Josiah Hotchkiss Gilbert, Dictionary of Burning Words of Brilliant Writers (1895), p. 54