by his learning the craft of electrical machinery, do we say that one offsets the other? No. Rather, we say: he must compensate the owner for the loss caused by the loss of writing, while the increase in his value due to the craft of electrical machinery belongs to the owner.

His statement, “And if it learns or gains weight, so that its value increases, then forgets,” refers to the case of learning.

His statement, “or becomes emaciated,” refers to the case of gaining weight.

His statement, “so that its value decreases,” means its monetary value.

His statement, “he is liable for the increase”: an example is a man who usurps an unskilled slave with no knowledge of a trade, teaches him, and he learns, so that his value increases; then he forgets, and his value decreases. If his value before learning was ten, then became twenty after learning, and returned to ten when he forgot, the author says: “He is liable for the increase” that resulted from learning. This is because his value increased through learning while he remained the property of his owner, but that increase was lost while he was under the usurper’s liability. Thus, the usurper is liable for the increase.

Likewise, if he gains weight after being usurped—for example, if someone usurps an emaciated sheep, feeds it until it becomes fat, and then it returns to being emaciated—is he liable for the increase that occurred? Yes, he is liable for it, because its increase took place while it belonged to its owner, whereas the loss occurred while it was under the usurper’s liability.

His statement, “just as if it were restored by something of a different kind from the original,” means: just as if the craft were restored by one different from the original. For example, he usurps an unskilled slave who knows no trade; the slave then learns carpentry and becomes skilled and proficient in it, but later forgets it and learns blacksmithing, becoming accomplished at it. Is he liable for the loss when his value decreased