Beneath the ancient slopes of Mount Etna, magma does not follow a single path to the surface — it chooses, in a sense, between patience and urgency. Cornell researchers have discovered that the invisible gases locked within rising rock, particularly the balance between carbon dioxide and water vapor, determine whether an eruption unfolds over weeks or within hours. This finding, drawn from crystals formed in eruptions thousands of years apart, invites us to reconsider what we thought we understood about the deep forces that shape volcanic violence — and how much of the Earth's inner life remai