We cannot observe external things without some degree of Thought; nor can we reflect upon our Thoughts, without being influenced in the course of our reflection by the Things which we have observed.

The object of science is knowledge; the objects of art are works. In art, truth is the means to an end; in science, it is the only end. Hence the practical arts are not to be classed among the sciences

According to the technical language of old writers, a thing and its qualities are described as subject and attributes; and thus a man's faculties and acts are attributes of which he is the subject. The mind is the subject in which ideas inhere. Moreover, the man's faculties and acts are employed upon external objects; and from objects all his sensations arise. Hence the part of a man's knowledge which belongs to his own mind, is subjective: that which flows in upon him from the world external to him, is objective.

We cannot observe external things without some degree of Thought; nor can we reflect upon our Thoughts, without being influenced in the course of our reflection by the Things which we have observed.

The catastrophist constructs theories, the uniformitarian demolishes them.

Man is the interpreter of nature, science the right interpretation.

Astronomy is ... the only progressive Science which the ancient world produced.