Here you will find the Poem Prosody 101 of poet Linda Pastan
When they taught me that what mattered most was not the strict iambic line goose-stepping over the page but the variations in that line and the tension produced on the ear by the surprise of difference, I understood yet didn't understand exactly, until just now, years later in spring, with the trees already lacy and camellias blowsy with middle age, I looked out and saw what a cold front had done to the garden, sweeping in like common language, unexpected in the sensuous extravagance of a Maryland spring. There was a dark edge around each flower as if it had been outlined in ink instead of frost, and the tension I felt between the expected and actual was like that time I came to you, ready to say goodbye for good, for you had been a cold front yourself lately, and as I walked in you laughed and lifted me up in your arms as if I too were lacy with spring instead of middle aged like the camellias, and I thought: so this is Poetry!