40. And such is Nature's law divine, that those Who grow together cannot choose but love, If faith or custom do not interpose, Or common slavery mar what else might move All gentlest thoughts; as in the sacred grove _2690 Which shades the springs of Ethiopian Nile, That living tree which, if the arrowy dove Strike with her shadow, shrinks in fear awhile, But its own kindred leaves clasps while the sunbeams smile; 41. And clings to them, when darkness may dissever _2695 The close caresses of all duller plants Which bloom on the wide earth--thus we for ever Were linked, for love had nursed us in the haunts Where knowledge, from its secret source enchants Young hearts with the fresh music of its springing, _2700 Ere yet its gathered flood feeds human wants, As the great Nile feeds Egypt; ever flinging Light on the woven boughs which o'er its waves are swinging. 42. The tones of Cythna's voice like echoes were Of those far murmuring streams; they rose and fell, _2705 Mixed with mine own in the tempestuous air,-- And so we sate, until our talk befell Of the late ruin, swift and horrible, And how those seeds of hope might yet be sown, Whose fruit is evil's mortal poison: well, _2710 For us, this ruin made a watch-tower lone, But Cythna's eyes looked faint, and now two days were gone 43. Since she had food:--therefore I did awaken The Tartar steed, who, from his ebon mane Soon as the clinging slumbers he had shaken, _2715 Bent his thin head to seek the brazen rein, Following me obediently; with pain Of heart, so deep and dread, that one caress, When lips and heart refuse to part again Till they have told their fill, could scarce express _2720 The anguish of her mute and fearful tenderness, 44. Cythna beheld me part, as I bestrode That willing steed--the tempest and the night, Which gave my path its safety as I rode Down the ravine of rocks, did soon unite _2725 The darkness and the tumult of their might Borne on all winds.--Far through the streaming rain Floating at intervals the garments white Of Cythna gleamed, and her voice once again Came to me on the gust, and soon I reached the plain. _2730 45. I dreaded not the tempest, nor did he Who bore me, but his eyeballs wide and red Turned on the lightning's cleft exultingly; And when the earth beneath his tameless tread, Shook with the sullen thunder, he would spread _2735 His nostrils to the blast, and joyously Mock the fierce peal with neighings;--thus we sped O'er the lit plain, and soon I could descry Where Death and Fire had gorged the spoil of victory.