strikingly exhibited in the check, which he gave to the expectations of his auditors, in the prefatory address to his Lectures: he desired them expressly to understand, that he could not give them real principles for the proper foundation of science. He informed them that he was continually changing his opinions, and probably might do so every year, and therefore they must be prepared to hear him change his views also. This clearly shews the distinction he made between opinions and first truths. He felt that the opinions that he had formed, had not undergone the test of absolute truth, and were therefore unfit to build the structure of science upon. They had not the proper stamp to give them legal currency; and yet he saw the possibility of their getting, by the authority of his name, the value of a genuine coin. The practice of giving the weight of authority to the opinions of lecturers, has the certain effect of shackling and narrowing the minds of students, and of
