instrument, and not as the object of their researches. They did not turn a reflective eye upon the instrument or medium through which their observations were made. Just as the astronomer does not look at his telescope, but looks through it at the stars, so the Sophists overlooked thought itself, and attended merely to what was revealed to them through its means. But, in consequence of this oversight, their analysis was exceedingly defective; because, while it is quite proper that the astronomer should overlook his instrument, the telescope, inasmuch as some star, or whatever the object may be, is all that he is professing to examine, it is by no means proper that thought, the instrument of the philosopher, should be overlooked in the same way. Thought is not only the philosopher's instrument, it is also the object or part of the object which the philosopher is called upon to investigate and explain. He professes to examine human nature; if, therefore, he merely employs thought in the examination without making it part of the thing examined, he is not faithful to his calling, he is leaving out of the survey an element which the survey ought to embrace; his observations, accordingly, will be imperfect, and his report false and incomplete. This was what befell the investigations of the Sophists. Their report of human nature was defective, because it left out of account the element of thought, an element which, no less than sensation, although in a much less obtrusive degree than sensation, is a characteristic
