“Even though it always holds true, people couldn't comprehend the Lógos, not even after they've been told about it.
“Failure to understand it is the root of all evil. (Heraclitus, 450 BC)

“In it was life, and the life was the light of men. And the light in the darkness shined; and the darkness comprehended it not. (John 1:4-5)

Things get lost in translation. Lógos does not have its equivalent in modern languages (and Latin was already too modern) so it became "word" in Gospels. A placeholder, maybe? But then they couldn't think of anything, so it stayed. In yet another context, namely Euclid explaining geometrical proportions, lógos ended up as "ratio" — hence "rational". See what I mean?

I bet they tried to do Heraclitus as well, but couldn't get past "I told you so."