Such a logic could not avoid having for its salient features definition of what is already known (or thought to be known), and its systematization according to recognized canons of orthodoxy. A logic of discovery on the other hand looks to the future. Received truth it regards critically as something to be tested by new experiences rather than as something to be dogmatically taught and obediently received. Its chief interest in even the most carefully tested ready-made knowledge is the use which may be made of it in further inquiries and discoveries. Old truth has its chief value in assisting the detection of new truth. Bacon's own appreciation of the nature of induction was highly defective. But his acute sense that science means invasion of the unknown, rather than repetition in logical form of the already known, makes him nevertheless the father of induction. Endless and persistent uncovering of facts and principles not known--such is the true spirit of induction. Continued progress in knowledge is the only sure way of protecting old knowledge from degeneration into dogmatic doctrines received on authority, or from imperceptible decay into superstition and old wives' tales. Ever-renewed progress is to Bacon the test as well as the aim of genuine logic. Where, Bacon constantly demands, where are the works, the fruits, of the older logic? What has it done to ameliorate the evils of life, to rectify defects, to improve conditions? Where are the inventions that justify its claim to be in possession of truth? Beyond the victory of man over man in law courts, diplomacy and political administration, they are nil. One had to turn from admired "sciences" to despised arts to find works, fruits, consequences of value to human kind through power over natural forces. And progress in the arts was as yet intermittent, fitful, accidental. A true logic or technique of inquiry would make advance in the industrial, agricultural and medical arts continuous, cumulative and deliberately systematic. If we take into account the supposed body of ready-made knowledge upon which learned men rested in supine acquiescence and which they recited in parrot-like chorus, we find it consists of two parts. One of these parts is made up of the errors of our ancestors, musty with antiquity and organized into pseudo-science through the use of the classic logic. Such "truths" are in fact only the systematized mistakes and prejudices of our ancestors. Many of them originated in accident; many in class interest and bias, perpetuated by authority for this very reason--a consideration which later actuated Locke's attack upon the doctrine of innate ideas. The other portion of accepted beliefs comes from instinctive tendencies of the human mind that give it a dangerous bias until counteracted by a conscious and critical logic.