Why the S'Y?

Question

I have just run across this sentence in my reading, and I don't understand how/why the adverbial pronoun is used:

The introductory sentence is part of a conversation:

-Vous ignorez qu'il est le propriétaire des parfums et des produits de beauté Mylène?

This is followed by the following sentence, which is the author's omnipotent observation about how little Maigret knew about perfumes:

Il s'y connaissait si peu en produits de beauté!

I understand what is being communicated, but I don't understand the grammar!

Please explain why the "s'y" construction is in this sentence.

Merci!

Accepted Answer

HI Jamie,
The expression "s'y connaitre en quelque chose" means "to be well versed in, to have a good knowledge of something"
Hope this helps,
Tom

Answer

So that entire expression is an idiomatic construction?  Cool!  No wonder I couldn't figure it out!Thanks, Tom