It would be difficult to overestimate the influence and importance of John Locke's life and writings on the subsequent history of the western world.
Thomas Jefferson referred to Locke as one of "the three greatest men that have ever lived, without any exception." In writing the Declaration of Independence, Jefferson drew heavily on the doctrines concerning the general principles of liberty and the rights of man which Locke set forth in his work; Of Civil Government. In particular, in the first draft of the Declaration of Independence, Jefferson copied Locke's words, "Life, liberty and property" which were subsequently changed to "Life, liberty and the pursuit of happiness."
Locke's influence is easily perceived in the work of not only Jefferson, but Alexander Hamilton, Jonathan Edwards, Jeremy Bentham, John Stuart Mill, Voltaire, Montesquieu, Leibnitz (as an opponent) and Kant.
Locke's influence and importance are succinctly and accurately summed up by R.I. Aaron, Professor of Philosophy, University of Wales, who hailed him as the initiator of the age of enlightenment and reason and an inspirer of the Constitution ...and more than a quarter of a millennium after his death, still a powerful influence on the life and thought of the West.
The key to Locke's prominence in
'bringing the world out of the dark ages'
is his treatise
³Essay concerning Human Understanding².
This work stands as one of the greatest advancements in world history.
In this monumental work, Locke examines many topics of human existence and thought; God, the soul, knowledge, freedom, will, ideas, liberty of thought, power, identity, morals, etc..
Locke's outline of the sections of his chapter on freedom and will gives a sense of the direction he follows; (Document #71593)
28. Volition is the ordering of some action by thought.
29. Uneasiness determines the will.
30. Will must be distinguished from desire.
31. The greater good in view barely consider'd determines not the will. The joys of heaven are often neglected.
32. Desire determines the will.
33. Desire is an uneasiness.
34. The greatest present uneasiness usually determines the will, as is evident in experience.
35. Because uneasiness being a part of unhappiness which is first to be removed in our way to happiness.
36. Because uneasiness alone is present.
37. The uneasiness of other passions have their share with desire.
38. Happiness alone moves the desire.
39. All absent good not desired, because not necessary to our happiness.
40. The greatest uneasiness does not always determine the will, we can suspend the execution of our desires.
Locke's major hypothesis is that man is born with no knowledge, like a clear blackboard.... Knowledge is gained by the input from the five senses-and the experiences so entered fill the blackboard and create the knowledge.
Most of Locke's reasoning is very difficult to analyze, even now, 300 years later, but the importance in his work is the fact that no one had ever before propounded such a subject of consideration. As he himself put it; (Document #32893)
". . . My notions in this treatise has run me . . . far out of the common road and practice. . ."
As an example, in one letter Locke begins, "Thought can never begin to be", referring to the fact experiences must enter through the senses in order to formulate thought. This particular passage then proceeds through a complex path of reasoning and finally concludes (!!) that; God must therefore be spiritual and not material; (Document #10292/3)
Thought can never begin to be: for it is impossible to conceive that matter; either with or without motion, could have originally in and from itself sense, perception, and knowledge, as is evident from hence, that sense, perception and knowledge must then be a property eternally inseparable from matter, and every particle of it. Not to add, that though our general or specific conception of matter makes us speak of it as one thing, yet really all matter is not one individual thing, neither is there any such thing existing as one material being or one body, that we know or can conceive. And therefore, if matter were the eternal first cogitative being, there would not be one eternal infinite cogitative being; but an infinite number of finite cogitative beings, independent one of another, of limited force and distinct thoughts, which could never produce that order, harmony and beauty as to be found in nature. Since therefore whatsoever is the first eternal being must necessarily be cogitative; and whatsoever is first of all things . . . higher degree, it necessarily follows, that the eternal first being cannot be matter".
Locke also discusses, in detail, the difference between an object and the idea representing the object.