Poetry carries its history within it, and it is oral in origin. Its transmission was oral.

Modernism in other arts brought extreme difficulty. In poetry, the characteristic difficulty imported under the name of modernism was obscurity. But obscurity could just as easily be a quality of metrical as of free verse.

I've not been a prolific poet, and it always seemed to me to be a bad idea to feel that you had to produce in order to get... credits. Production of a collection of poems every three years or every five years, or whatever, looks good, on paper. But it might not be good; it might be writing on a kind of automatic pilot.

The voice is raised, and that is where poetry begins. And even today, in the prolonged aftermath of modernism, in places where "open form" or free verse is the orthodoxy, you will find a memory of that raising of the voice in the term "heightened speech".

A glance at the history of European poetry is enough to inform us that rhyme itself is not indispensable. Latin poetry in the classical age had no use for it, and the kind of Latin poetry that does rhyme - as for instance the medieval Carmina Burana - tends to be somewhat crude stuff in comparison with the classical verse that doesn't.

At four lines, with the quatrain, we reach the basic stanza form familiar from a whole range of English poetic practice. This is the length of the ballad stanza, the verse of a hymn, and innumerable other kinds of verse.

I don't see that a single line can constitute a stanza, although it can constitute a whole poem.