How Does a Poem Mean?

I have experienced this book in several editions. The operative word in the title is "how." As an amateur poet for whom finding the technical construction of a "poem," or even something so prosaic as the very definition of poetry, this book over the past 40 years has been vital. Ciardi takes the word craft down to basic tools of craftsmanship, such as a pinter wild word with such basic as palate, paint, canvas, easel, brushes, etc. Probably his best chapter is that taht tells why a much beloved poem like
"Invictus" isa very bad poem, changed my whole way of looking at my own work. The example poems in the book, which have changed some from one edition to the next, are themselves very important. This is is a must book for both writers and readers.