 There is, Maritain holds, a single natural law governing all beings with a human nature. The first principles of this law are known connaturally, not rationally or through concepts, by an activity that Maritain, following Aquinas, called synderesis. Thus, natural law is ‘natural’ because it not only reflects human nature, but is known naturally. Maritain acknowledges, however, that knowledge of the natural law varies throughout humanity and according to individuals’ capacities and abilities, and he speaks of growth in an individual’s or a collectivity’s moral awareness. This allows him to reply to the challenge that there cannot be a universal, natural law because no such law is known or respected universally. Again, though this law is progressively known, it is never known completely, and so the natural law is never exhausted in any particular articulation of it (La loi naturelle, see Sweet 1998). This recognition of the historical element in human consciousness did not, however, prevent Maritain from holding that this law is objective and binding. (Critics have argued, however, that to speak of ‘connatural knowledge’ is obscure; it is quite unlike what we ordinarily call ‘knowledge’ and is, therefore, inadequate as a basis for knowledge of law. [see, for example, Nielsen 1959 [1991].)