In every department of physical science there is only so much science, properly so-called, as there is mathematics. – Immanuel Kant
He who is cruel to animals becomes hard also in his dealings with men. We can judge the heart of a man by his treatment of animals. – Immanuel Kant
Metaphysics is a dark ocean without shores or lighthouse, strewn with many a philosophic wreck. – Immanuel Kant
Intuition and concepts constitute… the elements of all our knowledge, so that neither concepts without an intuition in some way corresponding to them, nor intuition without concepts, can yield knowledge. – Immanuel Kant