As the theories of the schoolmen subside, and men no longer ignore nature, it will become recognised as the source rather than the tool of intellect. We shall have less occasion to contend that all lofty and sublime ideas derive their value and beauty from their coherence with the instincts of sensation, 'Poetry, we grant, creates a world of its own; but it creates it out of _existing_ materials.' 'Imagination' may be but 'thought on fire,' but the spark, which ignites it, is material. Is there any other distinction between the nights of the rhapsodist and those of genius, than that genius _illumines_ reality and rhapsody _obscures_ it? 'We know of no great generalisation that has ever been made by a man unacquainted with the details on which it rests.' Experiment is invented observation. It is putting into operation certain supposed causes in order to observe their effects. An experiment may be defined as an observation, which we are at some trouble to make. Experiment is usually set down as being a process of discovering truth different from observation. It is evidently included under observation, and there is no practical advantage in separating it. Discursive, general, ordinary, or common observation is the observation of the phenomena we _find_. Experiment is observation of the phenomena we _bring together_. Experimental observation has been the great agent of modern discovery. Newton ranked it as the most valuable knowledge. Whatever is not founded on phenomena is hypothesis, and has no place in experimental philosophy. It is the principal source of accurate facts. When Jenner first communicated to John Hunter, what he thought respecting the prevention of small pox--'Don't think, but try; be patient, be accurate,' was Hunter's characteristic reply. Locke remarks--'While the philosophy of Aristotle prevailed in the schools, which dealt often in words without meaning, the knowledge of nature was at a stand; men argued concerning things of which they had no idea; in this enlightened age, we keep to trial and experiment, as the only certain foundation of philosophy.' * Philosophy and Religion of Shakspere, pp. 173-4 ** No 946. p. 1103. *** Athenaeum, No. 946, p. 1191.