“In the knowledge of nature," Aristotle writes, the test of principles "is the unimpeachable evidence of the senses as to the fact." He holds that "lack of experience diminishes our power of taking a comprehensive view of the admitted facts. Hence those who dwell in the intimate association with nature and its phenomena grow more and more able to formulate, as the foundation of their theories, principles such as to admit of a wide and coherent development; while those whom devotion to abstract discussions has rendered unobservant of the facts are too ready to dogmatize on the basis of a few observations.”

Source: Theory of the Earth (Paper, published in Transactions of the Royal Society of Edinburgh in 1785)

Great Books: The Foundation of a Liberal Education (1954)

Power of the Master Mind
Source: Think & Grow Rich, January 1963, p. 150.

Source: The Principles of Science: A Treatise on Logic and Scientific Method (1874) Vol. 1, p. 14

139
Saint Genet, Actor and Martyr (1952)

Source: General System Theory (1968), 2. The Meaning of General Systems Theory, p. 32

Source: 1940s, The Elements of Business Administration, 1943, p. 118

A Preliminary Discourse on the Study of Natural Philosophy (1831)
Context: We must never forget that it is principles, not phenomena, — laws not insulated independent facts, — which are the objects of inquiry to the natural philosopher. As truth is single, and consistent with itself, a principle may be as completely and as plainly elucidated by the most familiar and simple fact, as by the most imposing and uncommon phenomenon. The colours which glitter on a soapbubble are the immediate consequence of a principle the most important, from the variety of phenomena it explains, and the most beautiful, from its simplicity and compendious neatness, in the whole science of optics. If the nature of periodical colours can be made intelligible by the contemplation of such a trivial object, from that moment it becomes a noble instrument in the eye of correct judgment; and to blow a large, regular, and durable soap-bubble may become the serious and praise-worthy endeavour of a sage, while children stand round and scoff, or children of a larger growth hold up their hands in astonishment at such waste of time and trouble. To the natural philosopher there is no natural object unimportant or trifling. From the least of nature's works he may learn the greatest lessons. The fall of an apple to the ground may raise his thoughts to the laws which govern the revolutions of the planets in their orbits; or the situation of a pebble may afford him evidence of the state of the globe he inhabits, myriads of ages ago, before his species became its denizens.
And this, is, in fact, one of the great sources of delight which the study of natural science imparts to its votaries. A mind which has once imbibed a taste for scientific inquiry, and has learnt the habit of applying its principles readily to the cases which occur, has within itself an inexhaustible source of pure and exciting contemplations. One would think that Shakspeare had such a mind in view when he describes a contemplative man as finding

Introductory sentence of [Georg Simon Ohm, The Galvanic Circuit Investigated Mathematically, translated by William Francis, D. Van Nostrand Co, 1891, 11]