For in groping about amongst the forms of nature, whose reciprocal agreement with common empirical but higher laws would otherwise be regarded by the power of judgement as entirely contingent, it would be even more contingent if individual perceptions lent themselves so luckily to formulation in terms of an empirical law; but it would be all the more contingent if manifold empirical laws simply happened to be fitted for the systematic unity of our knowledge of nature in a wholly interconnected possible experience, unless, by means of an a priori principle, we presupposed nature to possess such a form.