Variant spelling of Ernest, from Old High German Ernust meaning vigor or battle to the death. The Earnest spelling was used in Victorian England; Oscar Wilde's play The Importance of Being Earnest made it famous.
Vibe
gentle
How it ages.
Antique and literary; the variant spelling adds a charming old-world quality.
The cultural moment.
Used in the US and UK in the 19th and early 20th centuries; rare but feeling vintage-ready.