Grammar · Chapter 36
因而 and 以便: 'so' and 'in order to'
cause，因而 + result · action，以便 + purpose
Both open the second half of the sentence. 因而 is a written 'so': first the cause, then the result (他病了，因而没来). 以便 is 'so that': first the action, then its purpose (早点走，以便赶车). In speech you would usually say 所以 and 为了.
Examples
- 他病了，因而没来。 Tā bìng le, yīn'ér méi lái. He fell ill, so he didn't come.
- 我累了，因而早睡。 Wǒ lèi le, yīn'ér zǎo shuì. I was tired, so I went to bed early.
- 早点走，以便赶车。 Zǎodiǎn zǒu, yǐbiàn gǎn chē. Leave early so you can catch the bus.