Through a variety of channels, especially Neo-Platonism and St. Augustine, these ideas found their way into Christian theology; and great scholastic thinkers taught that the end of man is to know True Being, that knowledge is contemplative, that True Being is pure Immaterial Mind, and to know it is Bliss and Salvation. While this knowledge cannot be achieved in this stage of life nor without supernatural aid, yet so far as it is accomplished it assimilates the human mind to the divine essence and so constitutes salvation. Through this taking over of the conception of knowledge as Contemplative into the dominant religion of Europe, multitudes were affected who were totally innocent of theoretical philosophy. There was bequeathed to generations of thinkers as an unquestioned axiom the idea that knowledge is intrinsically a mere beholding or viewing of reality--the spectator conception of knowledge. So deeply engrained was this idea that it prevailed for centuries after the actual progress of science had demonstrated that knowledge is power to transform the world, and centuries after the practice of effective knowledge had adopted the method of experimentation. Let us turn abruptly from this conception of the measure of true knowledge and the nature of true philosophy to the existing practice of knowledge. Nowadays if a man, say a physicist or chemist, wants to know something, the last thing he does is merely to contemplate. He does not look in however earnest and prolonged way upon the object expecting that thereby he will detect its fixed and characteristic form. He does not expect any amount of such aloof scrutiny to reveal to him any secrets. He proceeds to _do_ something, to bring some energy to bear upon the substance to see how it reacts; he places it under unusual conditions in order to induce some change. While the astronomer cannot change the remote stars, even he no longer merely gazes. If he cannot change the stars themselves, he can at least by lens and prism change their light as it reaches the earth; he can lay traps for discovering changes which would otherwise escape notice. Instead of taking an antagonistic attitude toward change and denying it to the stars because of their divinity and perfection, he is on constant and alert watch to find some change through which he can form an inference as to the formation of stars and systems of stars.