Last month, when I was suffering from a vertigo and unable to read for more than a few seconds at a time, my constant companion was the incomparable Ella Fitzgerald, and especially her four great Songbooks: Gershwin, Ellington, Cole Porter, and Rodgers & Hart. Collectively they constitute, I believe, one of the great achievements of 20th-century American art.

Ella recorded other “songbook” albums, including an Irving Berlin one, but these four are the masterpieces. And I might note that the Ellington songbook is different than the others, in two respects. First, here Ella sings with the composer and his orchestra; and second, the lyrics are undistinguished. Ella gets to show off her vocal chops, including scat singing — a style of which she is the undisputed champion — and that’s wonderful. But she doesn’t get to show us how she interprets great lyrics.

The other three Great Songbooks have her singing the words of some of the best lyricists of their (or any) time: Ira Gershwin, Lorenz Hart, and Cole Porter. The first two wrote lyrics to the music of others, while Porter wrote words for his own music. When the producer Norman Granz played Ella’s recordings of his songs, Porter said, “My, what marvelous diction that girl has” — a comment that has been taken as dismissive, but I don’t think it was. Porter would have heard his songs sung by many singers with lovely voices, but he had probably never heard a singer so intelligently attentive to his lyrics, of which he was very proud, and able to communicate their meaning clearly, vividly, and most musically. That would have captured his attention.

Ella indeed had marvelous diction, along with perfect pitch, a tone of exceptional purity from the top of her range to the bottom, and — something not often enough noted — great breath control. You never hear her breathe, no matter how long the line lasts or how fast the notes come. (This is a rare achievement. When Joni Mitchell, a great singer if there ever was one, sings “Twisted” — a vocalese gem that I don’t believe Ella ever recorded, though it was perfect for her — she nails every note but struggles to catch her breath. The only pop singer I can think of who has great breath control is k. d. lang, but she’s almost as freakishly talented as Ella.)

If you want to get started with this music, try these two songs: Rodgers and Hart’s “Bewitched, Bothered, and Bewildered” and the Gershwins’ “But Not For Me.” The latter is simply perfection: gorgeous and heartbreaking in the highest degree. I often think of what Ira Gershwin said: He knew that he and his brother had written some good songs, but he never knew just how good they were until he heard Ella sing them.