those who saw only a principle of rest, in nature and in themselves; there
were born Heracliteans or Eleatics, as there have been in later ages born
Aristotelians or Platonists. Like some philosophers in modern times, who
are accused of making a theory first and finding their facts afterwards,
the advocates of either opinion never thought of applying either to
themselves or to their adversaries the criterion of fact. They were
mastered by their ideas and not masters of them. Like the Heraclitean
fanatics whom Plato has ridiculed in the Theaetetus, they were incapable of
giving a reason of the faith that was in them, and had all the animosities
of a religious sect. Yet, doubtless, there was some first impression
derived from external nature, which, as in mythology, so also in
philosophy, worked upon the minds of the first thinkers. Though incapable
of induction or generalization in the modern sense, they caught an
inspiration from the external world. The most general facts or appearances
of nature, the circle of the universe, the nutritive power of water, the
air which is the breath of life, the destructive force of fire, the seeming
regularity of the greater part of nature and the irregularity of a remnant,
the recurrence of day and night and of the seasons, the solid earth and the
impalpable aether, were always present to them.

The great source of error and also the beginning of truth to them was
reasoning from analogy; they could see resemblances, but not differences;
and they were incapable of distinguishing illustration from argument.
Analogy in modern times only points the way, and is immediately verified by
experiment. The dreams and visions, which pass through the philosopher's
mind, of resemblances between different classes of substances, or between
the animal and vegetable world, are put into the refiner's fire, and the
dross and other elements which adhere to them are purged away. But the
contemporary of Plato and Socrates was incapable of resisting the power of
any analogy which occurred to him, and was drawn into any consequences