I suppose the most widely cited reason

大概最显而易见的原因就是
is simply the desire to acquire farmland.

古希腊人需要更多的土地
Remember, I keep emphasizing this.

我一直在强调
The vast overwhelming majority of people

当时古希腊拥有众多的人口
needed to farm land, in order to stay alive.

人们需要农田才能生存
And why should there be a shortage of farmland?

但是为什么当时的耕地会短缺呢
One answer,

原因之一是
and it's the one that is most widely believed among Greek scholars,

这个原因是被广大古希腊学者们所接受的
is that the growth of population that we have mentioned in connection

那就是人口的增长与城邦的数量
with the rise of the polis is still working once the polis comes into form.

在城邦兴起的阶段还是基本一致的
So what this means, if you used to have two children and now you have four,

比如一家过去有两个孩子现在多了两个
how do you provide for the extra two?

多了两张嘴怎么办呢