This is a book I reread frequently. Technically it's a children's book, but
has been a touchstone for me, and many other grown-ups!
The characters are all animals - Mole, Toad, Ratty, Badger & others —
who retain their intrinsic animal characteristics while being anthropomorphised: they row boats, make tea, wear clothes, drive cars etc.
There is humor, danger, combat and friendship. Tea is drunk, battles are fought, the friends come to each others aid in times of need. And more.
There is one chapter which stands apart from the rest of the book, and yet is considered to be its heart. The Piper at the Gates of Dawn brings Pan into the tale, and is where the book ceases to limit itself to the children's section of the shelf and moves comfortably over to Adult.
I don't have my copy at hand, but it's either AA Milne or PG Wodehouse who
posits the book as a test of character: give it to your betrothed, and if they don't like it, call off the wedding...it's that kind of book.