Our Ideas Are Only Intellectual Instruments Which

The Great Experimental Principle, Then, Is Doubt, That Philosophic Doubt Which Leaves To The Mind Its Freedom And Initiative, And From Which The Virtues Most Valuable To Investigators In Physiology And Medicine Are Derived.

Mediocre Men Often Have The Most Acquired Knowledge. It Is In The Darker. It Is In The Darker Regions Of Science That Great Men Are Recognized; They Are Marked By Ideas Which Light Up Phenomena Hitherto Obscure And Carry Science Forward.

First Causes Are Outside The Realm Of Science.

Theories Are Like A Stairway; By Climbing, Science Widens Its Horizon More And More, Because Theories Embody And Necessarily Include Proportionately More Facts As They Advance.

Priestley [said] That Each Discovery We Make Shows Us Many Others That Should Be Made.