“If a single cell, under appropriate conditions, becomes a man in the space of a few years, there can surely be no difficulty in understanding how, under appropriate conditions, a cell may, in the course of untold millions of years, give origin to the human race.”

Vol. I, Part III: The Evolution of Life, Ch. 3 : General Aspects of the Evolution Hypothesis; compare: "As nine months go to the shaping an infant ripe for his birth, / So many a million of ages have gone to the making of man", Alfred Lord Tennyson, Maud (1855)
Principles of Biology (1864)

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Herbert Spencer 81
English philosopher, biologist, sociologist, and prominent … 1820–1903

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Original: (zh-CN) 一切矛盾着的东西,互相联系着,不但在一定条件之下共处于一个统一体中,而且在一定条件之下互相转化,这就是矛盾的同一性的全部意义。列宁所谓“怎样成为同一的(怎样变成同一的),——在怎样的条件之下它们互相转化,成为同一的”,就是这个意思。

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