21. Yet his zeal, though free, was not so indiscreet, as to be its own herald upon every appearance of doing good; but was very circumspect in weighing all circumstances. Accordingly, in the same letter, he gives this wise advice, touching the order and measure which are necessary to be observed in this communication. “To some, we must lay open our hearts freely and exactly; to others more reservedly; to others we should be altogether locked up, concealing from them what we see no disposition in them to make a good use of.” *22. Zeal indeed should be always attended with prudence, to consider things well, and execute them in the best manner; to prevent mischiefs, or redress them with as much of sweetness, and as little acrimony as possible: and in desperate cases, or where the cure would prove worse than the disease, to suffer and pass them over; some souls having defects, as it were, incorrigible, which God permits to perfect them by humility; and others likewise, that have an intercourse with them, by patience and charity. *23. One great point of prudence requisite in a zealous man, is, neither to hurt his body by too much labour, nor his mind with too much business. As to the latter of these, M. _de Renty_ took especial care, so to manage all his works of charity, that his piety might not be hindered but advanced thereby, indispensably performing all his exercises of devotion; and while he conversed most with his neighbour, reserving a considerable part, both of the day and night, for conversing with God. As to the other, he thus expressed himself to a clergyman, who had impaired his health by extreme labour: “Give me leave, Sir, to tell you plainly, that you should not impose too much upon yourself, lest for want of moderation, you render yourself altogether unserviceable. The enemy usually takes no small advantage of such free and well-disposed natures; you are not your own, but a debtor to all men. Preserve yourself therefore, not by indulging your body, but by laying upon it no more than it is able to bear.” 24. Being at _Citry_, in the latter end of the year 1642, he had a strong impression upon his spirit, that at his return to _Paris_, he should find a new employment about the poor, and be much taken up therein. Accordingly, two days after his return thither, some persons came to advise with him, about a course of relieving all such poor in the city, as were ashamed to beg. He undertook to visit a fourth part of them, and to assist them according to their necessities. An employment sufficient to take up the whole time of one man, which yet he performed, notwithstanding the multitude of his other occupations; so that we must say, without a special assistance, he could not have done and suffered what he did; but God, who hath limited our strength of body, can increase it when and how he pleaseth.