A deliberately ambiguous phrase. Carries overtones of Original Sin, except that Housman seems to be pointing toward something even more “primal,” some uncorrectable or unredeemable “fault” in nature itself as opposed to just human nature.

A capstan is:

a vertical-axled rotating machine developed for use on sailing ships to apply force to ropes, cables, and hawsers.

The “cracked,” disused wooden capstan may suggest not only the hard times that have befallen the fishing industry here (see “decline in the population” below) but also a beached, aimless, or even broken feeling in the setting and perhaps the poet herself.

The word seraphim, literally “burning ones,” refers to a class of angels, the fifth-highest in the Jewish hierarchy and the highest in the Christian.

In this 1989 hit, Williams played Mr. Keating, an inspiring English teacher at a boys' private school.

Dead Poets Society script breakdowns available here.

The speaker, not wanting to believe the Captain is dead, begs him to revive.

Handwritten text of the poem, Walt Whitman, 1887

Filial: “of or due from a son or daughter.”

Victor Frankenstein learns to love his parents even more by contrast with the other, less happy parent-child relationships around him.

Proof that the word “tricksy” predates Gollum by over 300 years.

https://www.youtube.com/watch?v=O_aziIIp8U8

Referring to both the art form and the application of cosmetics.

Compare the famous references to cosmetic “painting” in Hamlet, e.g.:

Now get you to my lady’s chamber, and tell her, let her paint an inch thick, to this favour she must come… (V.i)

Slightly old-fashioned expression meaning “by the book,” “strictly according to the rules.” Edmond Hoyle was an English card game authority (17th-18th century) who lent his name to a popular series of rulebooks.