As clear fountains send forth pellucid streams, so do clear truths give accurate sciences. The more definite the facts, the more perfect the science; it is therefore of importance that all facts should be capable of being tested by the standard of physical certainty. Dr. Reid says, that 'the inquirer after truth must take only facts for his guide.' It is then of moment that he takes true and not false guides. A writer in the 'Monthly Repository' observes, that 'the basis of all knowledge is such an extensive induction from particular facts, as leads to general conclusions and fundamental axioms'--and if the facts are erroneous, evidently the conclusions will be also erroneous. He also remarks, that 'in reasoning, all sciences are the same, being founded on an examination of facts--comparison of ideas.' But If the examination is incomplete, or the facts admitted incorrect, the comparison will be alike defective and the reasoning vitiated. If suppositions or conjectures are mixed up with facts, the inductions from them will be suppositions, and the conclusions but conjectures. There are three words--consciousness, conscience, and conscientiousness--very much alike to the ear but very different in signification. Consciousness, is feeling--conscience, the sense of right and wrong---conscientiousness, the practice of what is believed to be right. Conscience and conscientiousness are often confounded. We say, lawyers have no conscience, we mean no conscientiousness. They know right from wrong as men, but not professionally. It is with consciousness that the logician has to deal. Consciousness is the primary source of knowledge. Consciousness and the 'Evidences of the Senses' are synonymous terms. Facts referable to consciousness are said to be physically certain. The evidence of the senses is the highest standard of certainty. The intuitive principles of belief are-- 1st. A conviction of our own existence. 2nd. A confidence in the evidences of our senses. 3rd. In our mental operations. 4th. In our mental identity. 5th. In the conformity of the operations of nature. These truths of intuition or consciousness are the foundation of all knowledge. Truths which we know, by way of inference, are occurrences which took place while we were absent--the events of history and the theorems of mathematics. But the truths known by intuition are the original premises from which all others axe inferred. Our assent to the conclusion being grounded upon the truth of the premises, we could never arrive at any knowledge by reasoning, unless something could be known antecedently to all reasoning.