Note 219 — CANTO III.
James Romanes Sibbald translation
Trembled, etc.: Symbolical of the increase of woe in Inferno when the doomed souls have landed on the thither side of Acheron. Hell opens to receive them. Conversely, when any purified soul is released from Purgatory the mountain of purification trembles to its base with joy (Purg. xxi. 58).