"Left to herself, the serpent now began,
To change; her elfin blood in madness ran." - These lines are written by -

John Keats:
- Born: October 31, 1795, London, England—
- Death: February 23, 1821, Rome, papal list.
- English Romantic lyric poet who devoted his short life to the perfection of a poetry. -
- His writings were marked by vivid imagery, great sensuous appeal, and an attempt to express a philosophy through classical legend.
- John Keats was apprenticed to a surgeon in 1811.

Best Works:
- Ode to Psyche
- Ode on Melancholy
- To Autumn
- Bright Star
- On First Looking into Chapman's Homer
- Lamia
- The Eve of St
- La Belle Dame sans Merci

Source: Britannica.com

These lines mentioned in the question are from the poem "Lamia".


Lamia [Left to herself]
John Keats

"Left to herself, the serpent now began
To change; her elfin blood in madness ran,
Her mouth foam'd, and the grass, therewith besprent,
Wither'd at dew so sweet and virulent;
Her eyes in torture fix'd, and anguish drear,
Hot, glaz'd, and wide, with lid-lashes all sear,
Flash'd phosphor and sharp sparks, without one cooling tear."