It is a commonplace that Roman law has no fully developed law of agency, particularly in the field of obligations. This seems generally to be regarded as a defect in the law arising from a lack of vision or an inability to overcome completely a rather primitive traditional rule, which prevents third parties from gaining the benefit of or being bound by the acts of others. Thus even the assertion of the fact that Roman law did not in principle accept agency in the modern sense carries something of a criticism of the law, and more or less veiled criticism of the absence of a developed law of agency appears in many treatments of the subject of agency in Roman law. Thus Thomas says of mandate that it “was the nearest approach that Roman law made towards the modern concept of agency; but it was a very imperfect form of agency”. Kaser refers to the ancient principle found in all peoples that a legal act produces effects only on the person taking part in it, and observes that the Romans adhered to this principle even in later times and extended it to informal acts from the formal acts in which its roots lay. He also comments that the idea that the acts of a party to a legal transaction can produce immediate effects on persons not involved in that transaction assumes a high degree of juristic abstraction and in its modern form is a conquest of modern times.