Purple is fashionable twice — Purple Emperor Butterfly

Purple-emperor is a kind of large butterfly, changed its shape twice in its life, from egg to caterpillar and then to butterfly. Inspired by the butterfly, Dickinson perceived herself transformed twice in her life. She selected purple-emperor due to its name, likely an emperor of poetry being on her mind.

Purple－is fashionable twice－
This season of the year,
And when a soul perceives itself
To be an Emperor.

(F.896/J.980)

[1, 4] Purple, Emperor:: a kind of butterfly called purple emperor.
[1] fashionable:: molded. twice:: from egg to caterpillar, then to butterfly.
[2] season of the year:: breeding period.

"Purple Emperor ... The surface of the wings, in the species above named, is dark brown, changing when seen in certain lights into purplish-blue of a very rich tint. ... When the Purple Emperor is within reach, no fly is more easily taken; for he is so very bold and fearless, that he will not move from his settling-place until you quite push him off; you may even tip the ends of his wings, and be suffered to strike him again." ─ The Naturalist's Library, Volume III (1835)

Key word's possible combinations:
• Purple-beech, -heron, -lily, -willow, -crow, -emperor, -finch, -martin, -shell.
• Soul-ale, -cake, -catcher, -doctor, -mate, -pennies.
• Emperor-fish, -goose, -moth, -penguin.