A dew sufficed itself
Reflexive grammar trick
"Sufficed itself"—grammatically weird. Dewdrops don't normally take reflexive verbs. Dickinson makes the dew self-contained, needing nothing external.
Scale reversal
The dew thinks it's accomplished something huge ("vast destiny") while dismissing actual life as trivial. Dickinson loves this kind of perspective flip.
Personification shift
Sun goes to "work," day goes to "play"—notice the sun gets the labor while the abstract "day" gets leisure. She's splitting the 24-hour cycle into competing characters.
Medical term
**Physiognomy** = the art of reading faces/appearances. The dew wasn't seen by anyone who could identify it—it vanished without witness.