  Letter 56: To your [Hugo Boxel] question as to whether I have as clear an idea of God as of a triangle, I reply in the affirmative. But if you ask me whether I have as clear a mental image of God as of a triangle, I reply in the negative. We cannot imagine God, but we can apprehend him by the intellect. Here it should also be observed that I do not claim to have complete knowledge of God, but that I do understand some of his attributes—not indeed all of them, or the greater part—and it is certain that my ignorance of very many attributes does not prevent me from having knowledge of some of them. When I was studying Euclid’s Elements, I understood early on that the three angles of a triangle are equal to two right angles, and I clearly perceived this property of a triangle although I was ignorant of many others.