'All the Phenomena of Physics,' says Professor Silliman, in his _First Principles of Philosophy_, 'are dependent on a limited number of general laws, _of which they are the necessary consequences_. However various and complex may be the phenomena, their laws are few, and distinguished for their exceeding simplicity. All of them may be represented by numbers and algebraic symbols, and these condensed _formulae_ enable us to conduct investigations _with the certainty and precision of pure Mathematics_. As in geometry, all the properties of figures are deduced from a few axioms and definitions; so _when the general laws of Physics are known, we may deduce from them, by a series of rigorous reasonings, all the phenomena to which they give rise_.' Auguste Comte, in his elaborate and encyclopaedic _Course of Positive Philosophy_, tells us that 'these _three_ laws [the Law of Inertia, the Law of the Equality of action and reaction, and the Law of the Composition of forces] are the experimental basis of the Science of Mechanics. From them the mind may proceed _to the logical construction of the Science, without further reference to the external world_. * * * We cannot, however, conceive of any case which is not met by these three laws of Kepler, of Newton, and of Galileo, and their expression is so precise that they can be immediately treated in the form of analytical equations easily obtained.' While also exhibiting the small number of Principles which lie at the foundation of other domains of our intellectual accumulations, Comte remarks: 'The ultimate perfection of the Positive system would be (if such perfection could be hoped for) to represent all phenomena as particular aspects of a single general fact;--such as Gravitation, for instance.'