"If fire go out and it find thorns" (Exodus 22:5). A person lights a fire on his own property, and it escapes. It reaches a neighboring field and destroys crops, haystacks, or standing grain. The Torah holds the one who lit the fire responsible. But the Mekhilta zeroes in on the word "thorns" and finds in it a crucial legal distinction.
Why does the verse mention thorns at all? Thorns are dry, flammable brush — the kind of material that catches a spark and carries it from one property to another. The Mekhilta reads the mention of thorns not as a mere detail of the scene but as a legal boundary marker. Thorns represent an intermediary. The fire did not leap directly from the arsonist's property to the victim's crops. It traveled through thorns first.
This intermediary matters enormously for liability. If thorns are present — if the fire spread through natural combustible material that happened to be between the two properties — then the person who lit the fire bears limited liability. He is responsible, but within defined bounds. The thorns represent an element of chance, a factor beyond the fire-starter's direct control.
But if no thorns are present — if the person lights a fire so close to his neighbor's property that it reaches the crops directly, without any intermediary — then there is no limit to his liability. He bears full responsibility for every bit of damage.
The Mekhilta transforms a single botanical detail into a foundational principle of tort law. The presence or absence of an intermediary between the harmful act and the resulting damage determines the scope of a person's obligation to pay.