MARK how the feathered tenants of the flood, br With grace of motion that might scarcely seem br Inferior to angelical, prolong br Their curious pastime! shaping in mid air br (And sometimes with ambitious wing that soars br High as the level of the mountain-tops) br A circuit ampler than the lake beneath-- br Their own domain; but ever, while intent br On tracing and retracing that large round, br Their jubilant activity evolves br Hundreds of curves and circlets, to and fro, br Upward and downward, progress intricate br Yet unperplexed, as if one spirit swayed br Their indefatigable flight.