[Notes: William Collins (1720-1756). A poet, who throughout life struggled with adversity, and who, though he produced little, refined everything he wrote with a most fastidious taste and with elaborate care.
Shell, according to a fashion common with the poets of the first half of the 18th century, stands for lyre. The Latin word testudo, a shell is often so used.
Possessed beyond the Muse's painting = enthralled beyond what poetry can describe.
His own expressive power, i.e., his power to express his own feelings.
In lightnings owned his secret stings = in lightning-like touches confessed the hidden fury which inspired him.
Veering song. The ever-changeful song.
Her wild sequestered seat. Sequestered properly is used of something which, being in dispute, is deposited in a third person's hands: hence of something set apart or in retirement.
Round a holy calm diffusing = diffusing around a holy calm.
Buskin. A boot reaching above the ankle. Gemmed = sparkling as with gems.
Faun and Dryad_. Creatures with whom ancient mythology peopled the woods.