This work tries to reconstruct the idea of dignitas naturae humanae in Wolff’s doctrine of natural law through the analysis of its two main elements: the equality among the human beings in their moral nature and the idea of perfectio naturalis, which characterises man’s condition as a creature. Therefore one aim at demonstrating that the complex semantic range of the concept of dignity finds its full expression in the faculty of the ethical subject to fulfil freely the natural duty. To this end, man is analysed in a double dialogical perspective: in relation to God and to the other living beings so as to underline his limitations, that is his labilitas, which is the cause of the unbridgeable hiatus existing between the most perfect Being and the human being on one side and man’s praestantia towards animals on the other side, according to the Christian doctrine which conceives man as master of the universe. Within this framework, the moral action, which is possible thanks to the labilitas of the human being in comparison with the divine perfection, is the clearest evidence of man’s praestantia towards the animals and
all the created beings, necessitated by their essence to the natural end. This praestantia is anchored in the exclusively human possibility to choose freely the good, rejecting the evil thanks to the rational and volitional faculty. Thus, freedom is that domain which, being not necessarily determined by the essence of the human soul, that is by the natural order wanted by God at the moment of the creation, permits man to pursue good, avoiding evil through the spontaneous fulfilment of the natural duty.