Learn French: Le poète ne sait où trouver sa muse pour ce recueil. - The poet does not know where to find his muse for this collection.

This is the main focus of your current lesson: the literary omission of pas. With a few specific verbs (most commonly savoir, pouvoir, oser, and cesser), formal and literary French often drops pas in negative sentences. Here, ne sait means exactly the same thing as ne sait pas.

Does this literary omission of pas apply to all verbs if I want to sound formal?

No, it is strictly limited to a handful of verbs. The core four are savoir, pouvoir, oser, and cesser. If you swapped savoir for a verb like comprendre, you would absolutely need to use the full ne comprend pas.

Why is trouver in the infinitive here instead of being conjugated?

Just like in English, French allows you to use a question word like où directly followed by an infinitive. This happens when the person doing the action (finding) is the same as the subject of the main verb (le poète). It acts as a neat shortcut for saying où il doit trouver (where he must find).

What exactly is a recueil?