Why is On his blindness a Petrarchan sonnet and not Miltonic Sonnet?

The poem "On His Blindness" by John Milton is not a Petrarchan sonnet but a Miltonic sonnet. Here's why:

1. Structure: A Petrarchan sonnet consists of two stanzas: an octave (eight lines) and a sestet (six lines), with a rhyme scheme of ABBA ABBA CDCDCD. Milton's "On His Blindness" has a different rhyme scheme of ABBA ABBA CDECDE, following the Miltonic sonnet form.

2. Shift: Petrarchan sonnets typically have a distinct "turn" or "volta" between the octave and the sestet, where the tone or subject matter shifts. In Miltonic sonnets, the shift often occurs after the eighth line, not between the octave and sestet. "On His Blindness" has the tonal shift after line eight, moving from lamenting his blindness to a more contemplative and resolute tone.

3. Length: Miltonic sonnets usually consist of fourteen lines, like the Petrarchan form, but their rhyme pattern is different. "On His Blindness" adheres to the fourteen-line structure common in both forms.

Therefore, "On His Blindness" is considered a Miltonic sonnet based on its specific rhyme scheme and distinct shift after line eight, aligning with the characteristics of the Miltonic sonnet form rather than the Petrarchan sonnet form.