"Measure Your Mind's Height By The Shade It Casts!"
Context: Fourteen years after Paracelsus, the German alchemist, left his friend Festus in his search for total knowledge, he pauses long enough to tell about his aspiration and failure. Festus, who has chosen a life of happy obscurity and has reared a family, had warned Paracelsus against trying to ignore human limitations; still, he admires the alchemist so much that he asks to hear about the struggle. Describing how he sought to know infinitely and thereby ignored God, Paracelsus tells that he could not love or recognize beauty; when he met the dying poet Aprile, he discovered his mistake, saw that he was a failure, and sank into a passive melancholy. He has publicly denounced the philosophers of Roman Catholicism and has loudly opposed Luther; he stands completely alone, having no one he can turn to or follow. But the memory of Aprile haunts him so that, as Festus attempts to raise him from his wretchedness, he slowly comes to see that he can aspire to be what the poet was–a man who loves infinitely. The quotation is from Festus' speech encouraging him to overcome his despair.
I know you and the lofty spirit you bear,And easily ravel out a clue to all.These are the trials meet for such as you,Nor must you hope exemption: to be mortalIs to be plied with trials manifold. . . .SinceThe rabbit has his shade to frighten him,The fawn a rustling bough, mortals their cares,And higher natures yet would slight and laughAt these entangling fantasies, as youAt rammels of a weaker intellect,–Measure your mind's height by the shade it casts!