A Trinity Riddle

I spread, descending,     a samite of stars.
White fingers bring me     for breakfast Mont Blanc,
and I develop     on earth's negative
the prints proving     a presence absent.
Rainbow-dancing,     my restless soft-self
teaches the sun at     his summer turn to
reprise in dawn-prisms     the light-praise of plants,
or stars in winter     the still song-homes
with brittle jewels     dropped bright from darkness,
or shifts my shape to     a shimmering self-trap.
NOW Speak, if you spy it,     the spECIal name
I bear in spring when     I baRE TAWdry alleys
to wear till dawn night-diamonds,     till dusk the jewel of time.