Fragrances.
As they held each other underneath the great pear tree, Toph seated in his lap, a terrible, excruciating stab of pain suddenly knifed through Kun's soul as he thought of how she could never see the blue of the spring sky, the dazzling ivory of the pear blossoms, the brilliant carmine of the peony blooms, enjoy the vivid orange of the chrysanthemums.
But then he remembered she could still smell the odor of growth in the warm spring air, the heady, wonderful fragrances of the flowers, the moist soil, and his own sharp, musky scent while he held her.
And for the blind earthbender, that was sufficient.