But it takes one to know one is probably the most familiar way of putting the point.

同类的事物才能互相认知也许这是说明这个观点最熟悉的方式。

It doesn't normally take one to know one.

所以一般不需要同类才能互知。

It takes one to know one.

需要一个人才能认识一个人。

Please. It takes one to know one.

拜托 你们半斤八两。

" It takes one to know one, " I thought, but I kept it to myself.

“知己知彼”，我想，但我把这个想法留给了自己。

So then he says, " Takes one to know one."

所以然后他说， “需要一个人去了解一个人。