In relation to this most important subject, read _Combe on the Constitution of Man_, a book, which I consider admirable for its broad, philosophic, and just views of the laws of the universe, in their bearing upon the constitution of our physical and moral nature. You are not unaware, that I had presented you similar views, and inculcated the same master principles, long before this excellent work was published. Thousands, in all ages, have entertained the same extended conceptions of the divine plan, and its bearing upon man and all beings, upon this and all other worlds. But the honor belongs to this author, to have given form and systematic arrangement to these views. I have given my thoughts upon this subject at the commencement of my letters, and have subjoined remarks upon the Christian religion at the close, because I deem that M. Droz, in not recurring to these fundamental principles at the beginning of his work, and in dwelling with so little earnestness upon the hope of the gospel, as an element of happiness, at the close, has left chasms in it which ought to be supplied. The sect, numerous in my day, in yours, I trust, will have disappeared, who hold that religion and philosophy are militant and irreconcilable principles. Such persons are accustomed to brand these broad views of Providence and moral obligation with the odium of impiety. You will hardly need my assurance, that, if I thought with them, _my right hand should forget its cunning_, before I would allow anything to escape my pen which might have the least tendency to impair in your minds the future and eternal sanctions of virtue. I shall hereafter enlarge upon my persuasion, that, so far from being in opposition, religion and philosophy, when rightly understood, will be found resting on the same immutable foundation. It is because the misguided friends of religion have attempted to sustain them, as separate and hostile interests, in my view, that the former has made so little progress towards becoming universal. It will one day be understood, that whatever wars with reason and common sense, is equally hostile to religion. The simple and unchangeable truths of Christianity will be found to violate none of our most obvious convictions. Truth will reassume her legitimate reign. Piety, religion and morals, our best interests for this life, and our surest preparations for a future one, will be found exactly conformable to the eternal order of things, and the system of the gospel will become universal, according to its legitimate claims. True piety, in my mind, is equally our duty, our wisdom and happiness. To behold God everywhere in his works, to hold communion with him in a contemplative and admiring spirit, to love, and trust him, to find, in the deep and constantly present persuasion of his being and attributes, a sentiment of exhaustless cheerfulness and excitement to duty, I hold to be the source of the purest and sublimest pleasure, that earth can afford.