One such book that I'm not reading out loud is Ludo and the Star Horse, by Mary Stewart, illustrated by Gino D'Achille (1974, reprinted in 2001). One snowy winter night in Bavaria, around 150 years ago, a young peasant boy named Ludo is left at home by his parents to look after the animals while they go down into the valley. He hears the stable door bang, and running to look, sees Renti, the old work horse, disappearing into the blizzard. Following after, Ludo finds himself falling through the snow into a cave that is the beginning of a magical journey through the signs of the zodiac.
The cave is the home of the Archer, Sagittarius. He tells Ludo that old Renti had deliberately left the stable, to seek the chariot of the sun and become a star horse. Before the sun passes through the 12 Houses of the Zodiac, Renti must catch up with it, or fail. Ludo, keeping faith with his old friend, sets off. Each House has its own guardian, not all of whom are friendly. Sneered at by Capricorn, helped by Aquarius, almost eaten by Pisces, Ludo and Renti press on, until at last they come to the house of the Scorpion. With the deadly tail of the Scorpion hanging over his head, and the Sun's chariot about to depart, Ludo must make a final choice for himself and his beloved horse.
A written description of the plot doesn't do justice the beauty of the book. This is the type of story that will make pictures in your mind that will last forever (as well as being illustrated with very engaging pictures of its own). It is also a book about growing up, and learning to trust yourself. At the book's beginning, Ludo is pretty sure he doesn't amount to much; by the end, he knows his own worth, and the value of having a dream.
A caveat: some people I know don't like this book because of its negative portrayal of their own sign of the zodiac. Gemini (twin bullying thugs), Cancer (murderous), and Pisces (also murderous) come off the worst, so be warned. But even though Capricorn is not entirely admirable, I still love this book!