Cognitive semantics postulates that metaphorical and metonymical mappings are involved in semantic changes. The author shows the weakness of this theory. It is better to look at the circumstances in collective experience that can explain the discrepancy between the new and the former meaning. He argues that a semantic change is often performed without its instigator's knowledge. He looks at a series of Latin polysemous words expressing not only a physical bond but also a juridical obligation. (Sabine De Knop)