For a long while I attempted, in vain, to excuse myself; I was at last obliged to yield: I insisted, however, for my reputation's sake, on a promise of secrecy. Every objection being removed, I wished to begin the subject, but found the commencement extremely difficult; for, with a person who was ignorant of natural philosophy, it was necessary to converse in a very circuitous manner, to prove that the earth was a planet, the other planets similar to the earth, and all the stars so many suns which enlightened a number of worlds. I once more assured her it would be much better to talk on such trifles as other people, in our situation, would amuse themselves with. In the end, however, to give her a general idea of philosophy, I pursued the following plan. All philosophy, said I, is founded on two things; an inquisitive mind, and defective sight; for if your eyes could discern every thing to perfection you would easily perceive whether each star is a sun, giving light to a number of worlds; on the other hand, had you less curiosity, you would hardly take the trouble to inform yourself about the matter, and consequently remain in equal ignorance; but the difficulty consists in our wanting to become acquainted with more than we see: besides, it is out of our power to understand much of what is even within the reach of our sight, because objects appear to us very different from what they are. Thus philosophers pass their lives in disbelieving what they see, and endeavouring to conjecture what is concealed from them; such a state of mind is not very enviable.