On the Origin of Species

As many more individuals of each species are born than can possibly survive; and as, consequently, there is a frequently recurring struggle for existence, it follows that any being, if it vary however slightly in any manner profitable to itself, under the complex and sometimes varying conditions of life, will have a better chance of surviving, and thus be naturally selected.

用一个长句清晰定义了自然选择的核心机制——过度繁殖→生存竞争→有利变异→自然选择；逻辑链完整，初学者可循，故清晰度为 88。

From these considerations, I shall devote the first chapter of this Abstract to Variation under Domestication... In the next chapter the Struggle for Existence amongst all organic beings throughout the world... will be treated of... This fundamental subject of Natural Selection will be treated at some length in the fourth chapter.

结构从已知（驯化变异）到未知（自然变异），从机制（自然选择）到证据（地质记录），先立后破（Ch.6 理论困难），逻辑环环相扣，故结构为 92。

It is preposterous to attribute to mere external conditions, the structure, for instance, of the woodpecker, with its feet, tail, beak, and tongue, so admirably adapted to catch insects under the bark of trees.

用啄木鸟的脚、尾、喙、舌的协同适应作为自然选择的例证——具体、可观察、反驳了"外部环境决定论"，故例证为 95。

Natural Selection almost inevitably causes much Extinction of the less improved forms of life and induces what I have called Divergence of Character.

自然选择驱动适应和性状分歧的核心机制被现代演化生物学充分验证；但 Darwin 的遗传理论（泛生论，pangenesis）完全错误，故准确性为 90。

The diversity of the breeds is something astonishing. Compare the English carrier and the short-faced tumbler, and see the wonderful difference in their beaks, entailing corresponding differences in their skulls.

从日常经验（鸽子育种）入手，逐步引入抽象概念；但 Ch.5 变异法则和 Ch.8 杂交不育的无限细节构成显著门槛，故可读性为 82。

Long before having arrived at this part of my work, a crowd of difficulties will have occurred to the reader. Some of them are so grave that to this day I can never reflect on them without being staggered.

Darwin 主动列出并回应了理论的主要困难（过渡形态缺失、复杂器官起源、本能、杂交不育）；但缺乏遗传机制和物种形成精确模型，故完整性为 88。

There is grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved.

提出了第一个自然主义的物种起源机制，统一了生物学的所有领域，改变了人类对自身在自然界位置的理解——这是科学史上最有影响力的范式革命之一，故创新性为 98。

It is interesting to contemplate an entangled bank, clothed with many plants of many kinds, with birds singing on the bushes, with various insects flitting about, and with worms crawling through the damp earth, and to reflect that these elaborately constructed forms, so different from each other, and dependent on each other in so complex a manner, have all been produced by laws acting around us.

清晰、克制、论证严密；"endless forms most beautiful" 等段落兼具科学精确与文学美感，故文笔为 85。