The Principia: Mathematical Principles of Natural Philosophy is Isaac Newton's monumental work, originally published in 1687. Known familiarly as the Principia, this text laid out in mathematical terms the principles of time, force, and motion that have guided the development of modern physical science.

Even after more than three centuries and the revolutions of Einsteinian relativity and quantum mechanics, Newtonian physics continues to account for many of the phenomena of the observed world. Newtonian celestial dynamics is still used to determine the orbits of our space vehicles.

This edition is a completely new translation, the first in 270 years, based on the third (1726) edition, the final revised version approved by Newton. It includes extracts from earlier editions, corrects errors found in previous versions, and replaces archaic English with contemporary prose and up-to-date mathematical forms.

Newton's principles describe acceleration, deceleration, and inertial movement; fluid dynamics; and the motions of the earth, moon, planets, and comets. A great work in itself, the Principia also revolutionized the methods of scientific investigation. It set forth the fundamental three laws of motion and the law of universal gravity, the physical principles that account for the Copernican system of the world as emended by Kepler, thus effectively ending controversy concerning the Copernican planetary system.

The illuminating Guide to the Principia by I. Bernard Cohen, along with his and Anne Whitman's translation, makes this preeminent work truly accessible for today's scientists, scholars, and students.

Thomas S. Kuhn's classic book The Structure of Scientific Revolutions is a landmark in intellectual history. It reshaped our understanding of the scientific enterprise and human inquiry in general. Kuhn challenged long-standing assumptions about scientific progress, arguing that transformative ideas don’t arise from the gradual process of experimentation and data accumulation, but instead occur outside of "normal science."

His ideas on how scientific revolutions bring order to the anomalies that amass over time in research experiments are still instructive in today’s biotech age. This essential work includes an insightful introduction by Ian Hacking, which clarifies terms popularized by Kuhn, including "paradigm" and "incommensurability," and applies Kuhn’s ideas to the science of today.

This edition is newly designed with an expanded and updated index, providing important background information as well as a contemporary context.