Learn French: La fatigue mentale ralentit la pensée, mais le jeu la stimule. - Mental fatigue slows down thought, but play stimulates it.

While mais (but) highlights a contrast, de même que (just as) highlights a parallel comparison. To draw an elegant parallel between these two opposite effects, you could rephrase it as: De même que le jeu stimule la pensée, de même la fatigue mentale la ralentit. (Just as play stimulates thought, so mental fatigue slows it down). Because de même que is followed by the indicative mood, the verb conjugations don't need to change.

What exactly does the "la" before "stimule" refer to, and why is it placed there?

The la is a direct object pronoun replacing the feminine noun la pensée (thought) to avoid repeating it. As a quick refresher: in French, object pronouns are placed directly in front of the conjugated verb they belong to. Even though English puts the pronoun at the end ("play stimulates it"), the French order must be subject-pronoun-verb: le jeu la stimule.

I usually translate "le jeu" as "the game." Why is it translated as the abstract concept of "play" here?

While un jeu indeed means "a game" (a specific activity with rules, like a board game), le jeu is also used as an uncountable noun to represent the broad, abstract concept of "play" or "playing". Because French requires definite articles (le, la, les) when talking about abstract concepts in a general sense, "play" becomes le jeu.

How can recognizing the root of the verb "ralentit" help me remember its meaning?