Evolution isn't *just* a theory. A scientific theory is one backed by empirical data and observation. This means that it is as close to a fact that it can become without actually experiencing it over millions of years.
These quotes are about the great phenomenon and what it means to earth.
I have called this principle, by which each slight variation, if useful, is preserved, by the term of Natural Selection.
I use the term Struggle for Existence in a large and metaphorical sense, including dependence of one being on another, and including (which is more important) not only the life of the individual, but success in leaving progeny.
As natural selection works solely by and for the good of each being, all corporeal and mental endowments will tend to progress towards perfection.
Man is descended from a hairy, tailed quadruped, probably arboreal in its habits.
The conversion of one species into another takes place by a leap.
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