| Quote #1
True Ease in Writing comes from Art, not Chance,
Art (or practice), not chance (or talent), decides the way these lines strut their stuff. As the speaker compares writing to dancing, he uses elision (the skipping of a syllable to conform to the number of feet per line). It's like he's showing off his fast step and enforcing the idea that writing verse and using techniques like elision are learned. It's also interesting to see how language and rules change over time: you probably wouldn't have pronounced learned with two syllables anyway, but you would pronounce easiest with three.
| Quote #2
'Tis not enough no Harshness gives Offence,
The speaker links prosody with content, but it's as if the term "sense" starts to mean more than just meaning or content. In connection with sound, which is one of the five physical senses, the use of "sense" begins to take on this other connotation. Poetry is a kind of "sound sense" that combines thoughts and prosody into one way of coming to know and experience the world.
| Quote #3
Soft is the Strain when Zephyr gently blows,
The rules of prosody become one and the same with nature – the soft wind, the smooth stream. These lines combine with lines 7-8 to highlight natural images and the way the meter of poetry can be shaped to sound like them.