In all these cases the loss or damage, as between the two innocent parties who are left face to face, may be considered as accidental. The rule of law has to determine as best it can on which side the loss should fall; and since by the hypothesis neither party has incurred moral blame, and this is the very cause of the difficulty, it is plain that the rules of ordinary social morality will afford no guidance. We have to resort either to considerations of general public expediency, or, if no obvious balance of convenience appears either way, to the purely technical application of rules already settled in less obscure matters. And this last method is not a mere evasion of the problem, but is a reasonable solution so far as no stronger reason can be assigned to the contrary. For the principle of certainty requires that a rule once settled shall be carried out to its consequences when no distinct cause is shown for making an exception or revising the rule itself. If any sense of hardship to the individual citizen remains after these considerations have been weighed, and it has also been observed that citizens have an equal chance of benefit as well as burden under special rules of this kind, it may be said that exposure to this kind of liability is part, and not a large part, of the price which the individual has to pay the State for the general protection afforded by its power, and the general benefit of its institutions.
Thus neither the work nor the field of legal science can be said to coincide with those of any other science; and the development of this, as of all other distinct branches of science, can be carried on only by the continuous effort of persons who make it the chief object of their attention in successive generations. This has been recognized in the institutions, both practical and academical, of all civilized nations. A civilized system of law cannot be maintained without a learned profession of the law. The formation and continuance of such a learned class can be and has been provided for, at different times and in different lands, in various ways, which it does not now concern us to mention in detail. It is not necessary for this purpose that the actual administration of justice should be wholly, or with insignificant exceptions, in the hands of persons learned in the law, though such is the prevailing tendency of modern judicial systems. It is enough that the learned profession exists, and that knowledge of the law has to be sought, directly or indirectly, in the deliberate and matured opinion of its most capable members. And the activity of modern legislation makes little or no difference to this; for we are not now speaking of the gen-
