Why is "en"used in this sentence?

[Yeli]

I am translating this text to learn but I can't understand why is "en"used here. Can someone help me with this?

La couleur, c'est par définition un paramètre qui fait peur à l'homme quand on en vient à parler de look, de style personnel et d'élégance.

[George Hunt]

It is a set phrase, "en venir à " .It means "come (around) to " -or something like that.

Th "en " is part of the expression as a whole and you don't really have to understand why (in my opinion) .

Do you understand the overall meaning now?

[Yeli]

yes, now I understand. thank you very much George.