"The questions whether the world has a beginning and its extension in space a boundary; whether there is anywhere, perhaps in my thinking self, an indivisible and indestructible unity, or whether there is nothing but that which is divisible and perishable; whether my actions are free or, like those of other beings, controlled by the strings of nature and fate; whether, finally, there is a supreme cause of the world, or whether natural things and their order constitute the ultimate object, at which all our consideration of things must stop - these are questions for whose solution the mathematician would gladly give up his entire science; for that science cannot give him any satisfaction in regard to the highest and most important ends of humanity."