Frogs were the ancestors of land vertebrates. 
Ancestral frog almost died. Had the ancestral frog of all humanity jumped two inches less on a certain occasion, the whole course of evolution would have been markedly changed.  From the briny waters of the seas there crawled out upon the land snails, scorpions, and frogs. They sprang suddenly from fish family. 
Among the land animals the frogs reached their climax in the preceding age and rapidly declined, but they survived because they could long live even in the drying-up pools and ponds of these far-distant and extremely trying times. They evolved into prereptiles in Permian.  Frogs are the only remaining group representative of man’s earlier ancestors. 
There is a saying about the importance of instilling loyalty in children: The quickest way for a tadpole to become a frog is to live loyally each moment as a tadpole.