In order to understand human neuromuscular function, Luigi Galvani had to face the problem relative to the way in which "animal electricity" may be stored in animal tissue. Searching for a solution, Galvani built a hybrid model which constitutes a "nested analogy". This model satisfies constraints provided by objects of his work environment. I defend the claim that the model visual structure is based on a factual or physical scenario—as opposed to counterfactual or imaginary. But this assertion does not imply that the visual structure comes from an existing structure recognized as the target.