which his fame most securely rests; but his influence on the philosophy of politics was so great
and so lasting that he must be treated as the founder of philosophical liberalism as much as of
empiricism in theory of knowledge.
Locke is the most fortunate of all philosophers. He completed his work in theoretical philosophy
just at the moment when the government of his country fell into the hands of men who shared his
political opinions. Both in practice and in theory, the views which he advocated were held, for
many years to come, by the most vigorous and influential politicians and philosophers. His
political doctrines, with the developments due to Montesquieu, are embedded in the American
Constitution, and are to be seen at work whenever there is a dispute between President and
Congress. The British Constitution was based upon his doctrines until about fifty years ago, and
so was that which the French adopted in 1871.
His influence in eighteenth-century France, which was immense, was primarily due to Voltaire,
who as a young man spent some time in England, and interpreted English ideas to his compatriots
in the Lettres philosophiques. The philosophes and the moderate reformers followed him; the
extreme revolutionaries followed Rousseau. His French followers, rightly or wrongly, believed in
an intimate connection between his theory of knowledge and his politics.
In England this connection is less evident. Of his two most eminent followers, Berkeley was
politically unimportant, and Hume was a Tory who set forth his reactionary views in his History
of England. But after the time of Kant, when German idealism began to influence English
thought, there came to be again a connection between philosophy and politics: in the main, the
philosophers who followed the Germans were Conservative, while the Benthamites, who were
Radical, were in the tradition of Locke. The correlation, however, is not invariable; T. H. Green,
for example, was a Liberal but an idealist.
Not only Locke's valid opinions, but even his errors, were useful in practice. Take, for example,
his doctrine as to primary and secondary qualities. The primary qualities are defined as those that
are inseparable from body, and are enumerated as solidity, extension, figure, motion or rest, and
number. The secondary qualities are all the rest: colour, sounds, smells, etc. The primary qualities,
he maintains, are actually in bodies; the secondary qualities, on the contrary, are