Why?
“That is mediocrity though it be called moderation.” – Friedrich Nietzsche
The last of the “nouns-set.” Past negative combines both past tense (which you’ve learned) and negative tense (which you’ve also learned) nouns. Now that you know both those things, you can learn past negative.
By learning the four noun-tenses, you’re also preparing yourself for the first particle (next chapter) as well as everything else (which focuses on nouns) in this season as well.