The greatest derangement of the mind is to believe in something because one wishes it to be so.
Louis PasteurAs in the experimental sciences, truth cannot be distinguished from error as long as firm principles have not been established through the rigorous observation of facts.
Louis PasteurEvery chemical substance, whether natural or artificial, falls into one of two major categories, according to the spatial characteristic of its form. The distinction is between those substances that have a plane of symmetry and those that do not. The former belong to the mineral, the latter to the living world.
Louis Pasteur