Skywriting

Three jets are streaking west:
Trails are beginning to fray already:
The third, the last set out,
Climbs parallel a March sky
Paying out a ruled white line:
Skywriting like an incision,
Such surgical precision defines
The mile between it and the others
Who have disappeared leaving behind
Only their now ghostly tracks
That still hold to the height and map
Their direction with a failing clarity:
The sky is higher for their passing
Where the third plane scans its breadth.
The mere bare blue would never have shown
That vaultlike curvature overhead,
Already evading the mathematics of the spot,
As it blooms back, a cool canopy,
A celestial meadow, needing no measure
But a reconnaissant eye, an ear
Aware suddenly that as they passed
No sound accompanied arrival or vanishing
So high were their flight-paths on a sky
That has gone on expunging them since,
Leaving a clean page there for chance
To spread wide its unravelling hieroglyphs.