"What we know, is a point to what we do not know." Open any recent journal of science, and weigh the problems suggested concerning Light, Heat, Electricity, Magnetism, Physiology, Geology, and judge whether the interest of natural science is likely to be soon exhausted.

The Complete Works of Ralph Waldo Emerson (Volume 1), Nature: Addresses, and Lectures, Nature, Chapter V (p. 39)