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

Every man has obligations which belong to his station. Duties extend beyond obligations, and direct the affections, desires, and intentions, as well as the actions.

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.

Conscience is the reason employed about questions of right and wrong.

In order that the facts obtained by observation and experiment may be capable of being used in furtherance of our exact and solid knowledge, they must be apprehended and analysed according to some Conceptions which, applied for this purpose, give distinct and definite results, such as can be steadily taken hold of and reasoned from.

The system becomes more coherent as it is further extended. The elements which we require for explaining a new class of facts are already contained in our system. In false theories, the contrary is the case.

Nobody since Newton has been able to use geometrical methods to the same extent for the like purposes; and as we read the Principia we feel as when we are in an ancient armoury where the weapons are of gigantic size; and as we look at them we marvel what manner of man he was who could use as a weapon what we can scarcely lift as a burden.