I have two sentences and would like to combine them using a relative clause.

  1. Those who don't learn from the past are doomed to repeat previous mistakes.

  2. Knowing previous mistakes helps us to avoid repeating those mistakes.

Can I say:

Those who don't learn from the past are doomed to repeat previous mistakes, knowing which helps us to avoid repeating those mistakes.

And is there some guide that I can read in regards to this topic?

  • I can't help noticing some sort of wordiness. I wouldn't go far after the first sentence because the idea is quite clear. You could finish your sentence and start a new one with a new subject and verb probably trying to capture a different aspect of the theme. Also if you'd like to continue, there is a shift in viewpoint that I don't find very attractive i.e. Those and suddenly us.
    – Yuri
    Feb 27, 2017 at 8:35
  • Thank you so much for the suggestions! But I still want to know, grammatically, if using a participle in front of a relative pronoun is acceptable. ("Knowing + which" as the subject of the clause?)
    – Sen Foo
    Feb 27, 2017 at 9:22
  • I see no problem with that grammatically ...repeat previous mistakes, learning lessons from which helps avoid making them in future that would be the least alteration of your original sentence though I believe you need to reconsider it. Also the participle might be considered by some as a dangling structure since there is not a word that we can refer to as the agent of the participle.
    – Yuri
    Feb 27, 2017 at 11:00

2 Answers 2


You're very close to correct, but I would say there are two issues.

Firstly, consider whether learning is supposed to be a participial adjective or a gerund. In the original sentence, it's a gerund, because it means the act of knowing helps us.

But when you stick that sentence on another sentence, it looks like a participial adjective, but then it doesn't make sense. The participial clause usually applies to the subject of the sentence. Consider "the birds flew by the window, chirping loudly" - clearly, the birds were chirping loudly, not the window. Likewise, the subject of the first sentence is those who don't learn from the past, so if you just stick on a participial clause, it sounds like it applies to those who don't learn, which is not what you want.

Secondly, if you want to make a dependent clause, it should begin with a subordinate conjunction like which, so you were almost correct, but it should be "...previous mistakes, which knowing helps us..."

If you want to make a completely separate independent clause (effectively a separate sentence), it needs a coordinating conjunction like and or but or a semicolon. For example:

"They are doomed to repeat previous mistakes, but knowing previous mistakes helps us..."
"They are doomed to repeat previous mistakes; knowing previous mistakes helps us..."

- Clauses and phrases
- Subordinate conjunctions


stangdon is right in his first point and wrong in his second. You CAN say "knowing which," although your particular sentence is quite clunky.

  • Hm, you might be right about that, now that I think about it. (BTW, this should probably be a comment on my answer, rather than a separate answer.)
    – stangdon
    Feb 28, 2017 at 23:41

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