The particles in question are てこそ and ば
The sentence I found them in is 競ってこそ花 負けて落ちれば泥. For context, the speaker has just met the listener.
てこそ is odd to understand because the way the sentence is translated and the definition that I searched does not seem to match up.
The sentence is translated to "Surely, if you compete against a flower, you will lose and fall in the mud".
On one hand, this does match up with the definition for こそ which is "for sure". However, てこそ is described as "now that" or "since".
The next particle I have trouble understanding is ば. If and then does not seem to fit here so I am assuming the particle is indicating supposition. Yet, if てこそ does mean "Surely", doesn't ば contradict that?