"The Sword in the Stone" shows White at his finest, creatively speaking. His depiction of life in the Forest Savage and of Arthur's entire childhood with Sir Ector and Kay is entirely his, and it is filled with enough detail and wit to enchant young readers into a lifelong love of Arthurian lore.
The book begins around the time Arthur is around seven or eight, still unaware of his parentage, and living in the care of Sir Ector. The book is riddled with memorable characters, charming buffoons, and (of course) Merlyn.
"The Once and Future King," of course, of which this is the first volume, was White's treatise on pacifism, as well as his exploration of the triumphs and failings of government, and you see a lot of this in "The Sword in the Stone." Arthur has a miserable time among the ants who are preparing for war; and falls in love with life among the geese, for whom war is a completely foreign concept. (Both stories appropriated from White's final and least impressive Arthurian work, "The Book of Merlyn.")
This is a phenomenal introduction to Arthurian legend. It inspired the Disney movie of the same name; and as part of "The Once and Future King," it inspired the musical "Camelot." I gave a copy to my 9-year-old, and it inspired her as well.