Comparing “běnlái” and “yuánlái”

我本来想去，但是后来没去。

Wǒ běnlái xiǎng qù, dànshì hòulái méi qù.

I originally wanted to go, but later I did not.

原来他就是你的老师。

Yuánlái tā jiù shì nǐ de lǎoshī.

So he turns out to be your teacher.

这件事本来不难，只是方法不对。 / 原来你早就知道了。

Zhè jiàn shì běnlái bù nán, zhǐshì fāngfǎ bú duì. / Yuánlái nǐ zǎo jiù zhīdào le.

This matter was not difficult in the first place; only the method was wrong. / So you already knew.