It is indeed Aprile's example and the fate which has overtaken him rather than his wild words which startle Paracelsus into a recognition of his own error.
But the knowledge that he has left love out of his scheme of life is no guarantee that he will ever acquire the fervour and the infinite patience of love.

The whole scene, with its extravagant poetic beauties and high-pitched rhetoric, leaves a painful impression of unreality, not in the shallower but in the deepest sense of that word.
For a poet to depict a poet in poetry is a hazardous experiment; in regarding one's own trade a sense of humour and a little wholesome cynicism are not amiss.

These could find no place in Browning's presentation of Aprile, but it is certain that Browning himself was a much more complex person than the dying lover of love who became the instructor of Paracelsus.

When the scene shifts from Constantinople to Basil, and the illustrious Professor holds converse with Festus by the blazing logs deep into the night, and at length morning arises "clouded, wintry, desolate and cold," we listen with unflagging attention and entire imaginative conviction; and, when silence ensues, a wonder comes upon us as to where a young man of three-and-twenty acquired this knowledge of the various bitter tastes of life which belong to maturer experience, and how he had mastered such precocious worldly wisdom.
Paracelsus, The wondrous Paracelsus, life's dispenser, Fate's commissary, idol of the schools And courts, chews upon his worldly success and extracts its acrid juices.

This is not the romantic melancholy of youth, which dreams of infinite things, but the pain of manhood, which feels the limitations of life, which can laugh at the mockery of attainment, which is sensible of the shame that dwells at the heart of glory, yet which already has begun to hanker after the mean delights of the world, and cannot dispense with the sorry pleasures of self-degradation.