when the west wind too, with his sweet breath, has breathed life into the tender shoots in every wood and heath, and the young sun has run his half course in the Ram,

Zephyrus is the west wind of Greek and Latin poetry, the wind of spring. Inspired keeps its Latin sense, “breathed into”: Skeat’s Glossary gives it here as “quickened,” brought to life. The croppes are the new growth at the ends of branches, and Skeat notes that this is why “to crop” came to mean cutting the tops off. The sun is “young” because the solar year was counted from the spring equinox, so in April the sun has only just begun its round. It has run “his half course in the Ram.” Skeat insists on reading this as it stands, a half course, against the older editor Tyrwhitt, who took it as “half his course.” In Chaucer’s time the sun was in Aries from March 12 to April 11, and April holds the second half of that passage, so the line says the date is past April 11. Chaucer wrote a treatise on the astrolabe for a boy he calls his son Lewis, and he liked to tell the time by the sky.