In other words, it was about sex and science, starting off with 'How the Chicken got inside the Egg', rambling through 'Some Other Sorts of Eggs' until arriving at 'What Little Boys and Girls are Made Of'. Brewster quoted 'the old nursery rhyme' and said that: It has this much truth in it, that little boys and little girls are far from being alike, and it isn't worth while trying to make either one over into the other.

换句话说，这本书讲到了性科学。它从「鸡怎么进到蛋里」开始谈起，谈到「其他种类的蛋」，直到「男孩和女孩是怎么产生的」。布鲁斯特还说：男孩与女孩确实是有区别的，但不要认为其中一方高于另一方。

The precise nature of this difference was not revealed, and only after a skilful diversion on to the subject of the eggs of starfish and sea-urchins did Brewster eventually arrive back at the human body:

这个区别是什么，布鲁斯特没有细说，他将话题引到了海星和海胆的卵，然回技巧性地回到人体上：

So we are not built like a cement or a wooden house, but like a brick one. We are made of little living bricks. When we grow it is because these living bricks divide into half bricks, and then grow into whole ones again. But how they find out when and where to grow fast, and when and where to grow slowly, and when and where not to grow at all, is precisely what nobody has yet made the smallest beginning at finding out.

所以，我们并不像泥马和木马，而是像用砖头砌成的马。我们是由小砖组成的，我们为什么能长大，就是因为一块砖分裂成两个半块，然后半块又能长成一整块。但是我们现在还搞不清楚，这些砖如何决定自己什么时候长，以及哪里长得快、哪里长得慢、哪里不长。

The process of biological growth was the principal scientific theme of E.T. Brewster's book. Yet science had no explanations, only descriptions. In fact on 1 October 1911, when Alan Turing's 'living bricks' were first dividing and redividing, Professor D'Arcy Thompson was telling the British Association that 'the ultimate problems of biology are as inscrutable as of old.'

生命的成长过程，是这本书里最重要的科学话题，但布鲁斯特并没给出详细的解释，他只是描述了这些现象。有意思的是，就在1911年10月1日，当艾伦?图灵的小砖第一次分裂的时候，生物学家达西?汤姆普森教授向英国学会报告说：生理学的本质问题，就像谜一样不可解。