I have procured air [oxygen] ... between five and six times as good as the best common air that I have ever met with.

Could we have entered into the mind of Sir Isaac Newton, and have traced all the steps by which he produced his great works, we might see nothing very extraordinary in the process.

How glorious, then, is the prospect, the reverse of all the past, which is now opening upon us, and upon the world. Government, we may now expect to see, not only in theory and in books but in actual practice, calculated for the general good, and taking no more upon it than the general good requires, leaving all men the enjoyment of as many of their natural rights as possible, and no more interfering with matters of religion, with men's notions concerning God, and a future state, than with philosophy, or medicine.

The wisdom of one generation will be folly in the next.

This is unfortunately a world in which things find it difficult, frequently impossible, to live up to their names.

In completing one discovery we never fail to get an imperfect knowledge of others.

Will is nothing more than a particular case of the general doctrine of association of ideas, and therefore a perfectly mechanical thing.