»Custodia«: At first glance, the sources on liability for custodia in Roman law are characterised by a fundamental inconsistency: on the one hand, the liability of a guardian appears as an automatic consequence of a theft of the thing left to him, on the other hand, as a consequence of a breach of due care. This discrepancy has triggered a pendulum movement in modern research. At one time custodia has been declared a guarantee liability, at another a form of liability for fault. The dilemma can only be solved if one seriously considers the limitation of the concept of theft in Rome.