Structural color, not pigment
The Morpho's blue is light bent by wing-scale ridges — it cannot fade, because nothing dyed it.
Mirrored arrangement holds the eye
Each specimen answers its twin across the axis, so the plate reads as one ordered cabinet, not a scatter.
Ochre warms what blue cools
Swallowtail amber sits beside the cold Morpho field, so neither tone flattens against the slate ground.
The cartouche carries the proof
Engraved plate number and Latin name fix each wing to its place — the record outlives the collector.