Metaphysics is a dark ocean without shores or lighthouse, strewn with many a philosophic wreck.
Immanuel KantInnocence is indeed a glorious thing; but, unfortunately, it does not keep very well and is easily led astray.
Immanuel KantThis can never become popular, and, indeed, has no occasion to be so; for fine-spun arguments in favour of useful truths make just as little impression on the public mind as the equally subtle objections brought against these truths. On the other hand, since both inevitably force themselves on every man who rises to the height of speculation, it becomes the manifest duty of the schools to enter upon a thorough investigation of the rights of speculative reason, and thus to prevent the scandal which metaphysical controversies are sure, sooner or later, to cause even to the masses.
Immanuel Kant