"But the secrets of courts are not revealed through spies; they get wind by means of certain people who are not in the least mistrusted; in like manner the best built ships leak through an imperceptible chink, which cannot be discovered.
"What is interesting in courts, and particularly so in ours," says MERCIER, "is that there is a degree of obscurity spread over all its proceedings. We wish to penetrate what is concealed, we endeavour to know till we learn; thus it is that the most ingenious machine preserves its highest value only till we have seen the springs which set it in motion.
"After having considered the different parts which form the police of the capital, we still perceive all the radii reaching from the centre to the circumference. How many ramifications issue from the same stem! How far the branches extend! What an impulse does not Paris give to other neighbouring cities!
"The police of Paris has an intimate correspondence with that of Lyons and other provincial cities: for it is evident that it would be imperfect, if it could not follow the disturber of public order, and if the distance of a few leagues skreened him from researches.
"The correspondence of the Parisian police is not therefore limited to its walls; it extends much farther; and it is in towns where imprudent or rash persons would imagine that they might give their tongue greater freedom, that the vigilant magistrate pries into conversation, and keeps a watchful eye over those who would measure their audacity by the degree of distance from the capital.
"Thus the police of Paris, after having embraced France, penetrates also into Switzerland, Italy, Holland, and Germany;[a]3]] and when occasion requires, its eye is open on all sides to what can interest the government. When it wishes to know any fact, it is informed of it to a certainty; when it wishes to strike a serious blow, it seldom misses its aim.
"It may easily be conceived that the machine would be incomplete, and that its play would fail in the desired effect, did it not embrace a certain extent. It costs but little to give to the lever the necessary length. Whether the spy be kept in pay at Paris, or a hundred leagues off, the expense is the same, and the utility becomes greater.
"Experience has shewn that these observations admit of essential differences in the branches of the police. Weights and measures must be changed, according to time, place, persons, and circumstances. There are no fixed rules; they must be created at the instant, and the most versatile actions are not destitute of wisdom and reason.
"Of this wholesale legislators are not aware: it is reserved for practitioners to seize these shades of distinction. There must be a customary, and, as it were, every-day policy, in order to decide well without precipitation, without weakness, and without rigour. What would be a serious fault at Paris, would be a simple imprudence at Lyons, an indifferent thing elsewhere, and so on reciprocally.
"Now this science has not only its details and its niceties, it has also its variations, and sometimes even its oppositions. Ministers must have a steady eye and great local experience, in order to be able to strike true, and strike opportunely, without espousing imaginary terrors; which, in matters of police, is the greatest fault that can be committed.[[4]]