Tazria: First in Thought or Last in Value?

Parsha Pick-Me-Up by Yitzchak Sprung

Episode notes

"If a man does well, they say to him, you preceded the angels; if he does not, they say to him: (in creation) the fly preceded you, the gnat preceded you, the snail preceded you." - Reish Lakish

But what does this have to do with the laws of Kashrut and ritual purity?