I refrain from considering here the other points of the Christian doctrine, and I will show only how Jesus Christ brought about the conversion of natural religion into law, and gained for it the authority of a public dogma. He alone did that which so many philosophers had endeavoured in vain to do; and Christians having at last gained the upper hand in the Roman Empire, the master of the greater part of the known earth, the religion of the wise men became that of the nations. Later also Mahomet showed no divergence from the great dogmas of natural theology: his followers spread them abroad even among the most remote races of Asia and of Africa, whither Christianity had not been carried; and they abolished in many countries heathen superstitions which were contrary to the true doctrine of the unity of God and the immortality of souls.
It is clear that Jesus Christ, completing what Moses had begun, wished that the Divinity should be the object not only of our fear and veneration but also of our love and devotion. Thus he made men happy by anticipation, and gave them here on earth a foretaste of future felicity. For there is nothing so agreeable as loving that which is worthy of love. Love is that mental state which makes us take pleasure in the perfections of the object of our love, and there is nothing more perfect than God, nor any greater delight than in him. To love him it suffices to contemplate his perfections, a thing easy indeed, because we find the ideas of these within ourselves. The perfections of God are those of our souls, but he possesses them in boundless measure; he is an Ocean, whereof to us only drops have been granted; there is in us some power, some knowledge, some goodness, but in God they are all in their entirety. Order, proportions, harmony delight us; painting and music are samples of these: God is all order; he always keeps truth of proportions, he makes universal harmony; all beauty is an effusion of his rays.
It follows manifestly that true piety and even true felicity consist in the love of God, but a love so enlightened that its fervour is attended by insight. This kind of love begets that pleasure in good actions which gives relief to virtue, and, relating all to God as to the centre, transports the human to the divine. For in doing one's duty, in obeying reason, one carries out the orders of Supreme Reason. One directs all one's intentions to the common good, which is no other than the glory of God. Thus one finds that there is no greater individual interest than to espouse that of the community, and one gains satisfaction for oneself by taking pleasure in the acquisition of true benefits for men. Whether one succeeds therein or not, one is content with what comes to pass, being once resigned to the will of God and knowing that what he wills is best. But before he declares his will by the event one endeavours to find it out by doing that which appears most in accord with his commands. When we are in this state of mind, we are not disheartened by ill success, we regret only our faults; and the ungrateful ways of men cause no relaxation in the exercise of our kindly disposition. Our charity is humble and full of moderation, it presumes not to domineer; attentive alike to our own faults and to the talents of others, we are inclined to criticize our own actions and to excuse and vindicate those of others. We must work out our own perfection and do wrong to no man. There is no piety where there is not charity; and without being kindly and beneficent one cannot show sincere religion.
Good disposition, favourable upbringing, association with pious and virtuous persons may contribute much towards such a propitious condition for our souls; but most securely are they grounded therein by good principles. I have already said that insight must be joined to fervour, that the perfecting of our understanding must accomplish the perfecting of our will. The practices of virtue, as well as those of vice, may be the effect of a mere habit, one may acquire a taste for them; but when virtue is reasonable, when it is related to God, who is the supreme reason of things, it is founded on knowledge. One cannot love God without knowing his perfections, and this knowledge contains the principles of true piety. The purpose of religion should be to imprint these principles upon our souls: but in some strange way it has happened all too often that men, that teachers of religion have strayed far from this purpose. Contrary to the intention of our divine Master, devotion has been reduced to ceremonies and doctrine has been cumbered with formulae. All too often these ceremonies have not been well fitted to maintain the exercise of virtue, and the formulae sometimes have not been lucid. Can one believe it? Some Christians have imagined that they could be devout without loving their neighbour, and pious without loving God; or else people have thought that they could love their neighbour without serving him and could love God without knowing him. Many centuries have passed without recognition of this defect by the people at large; and there are still great traces of the reign of darkness. There are divers persons who speak much of piety, of devotion, of religion, who are even busied with the teaching of such things, and who yet prove to be by no means versed in the divine perfections. They ill understand the goodness and the justice of the Sovereign of the universe; they imagine a God who deserves neither to be imitated nor to be loved. This indeed seemed to me dangerous in its effect, since it is of serious moment that the very source of piety should be preserved from infection. The old errors of those who arraigned the Divinity or who made thereof an evil principle have been renewed sometimes in our own days: people have pleaded the irresistible power of God when it was a question rather of presenting his supreme goodness; and they have assumed a despotic power when they should rather have conceived of a power ordered by the most perfect wisdom. I have observed that these opinions, apt to do harm, rested especially on confused notions which had been formed concerning freedom, necessity and destiny; and I have taken up my pen more than once on such an occasion to give explanations on these important matters. But finally I have been compelled to gather up my thoughts on all these connected questions, and to impart them to the public. It is this that I have undertaken in the Essays which I offer here, on the Goodness of God, the Freedom of Man, and the Origin of Evil.
There are two famous labyrinths where our reason very often goes astray: one concerns the great question of the Free and the Necessary, above all in the production and the origin of Evil; the other consists in the discussion of continuity and of the indivisibles which appear to be the elements thereof, and where the consideration of the infinite must enter in. The first perplexes almost all the human race, the other exercises philosophers only. I shall have perchance at another time an opportunity to declare myself on the second, and to point out that, for lack of a true conception of the nature of substance and matter, people have taken up false positions leading to insurmountable difficulties, difficulties which should properly be applied to the overthrow of these very positions. But if the knowledge of continuity is important for speculative enquiry, that of necessity is none the less so for practical application; and it, together with the questions therewith connected, to wit, the freedom of man and the justice of God, forms the object of this treatise.
Men have been perplexed in well-nigh every age by a sophism which the ancients called the 'Lazy Reason', because it tended towards doing nothing, or at least towards being careful for nothing and only following inclination for the pleasure of the moment. For, they said, if the future is necessary, that which must happen will happen, whatever I may do. Now the future (so they said) is necessary, whether because the Divinity foresees everything, and even pre-establishes it by the control of all things in the universe; or because everything happens of necessity, through the concatenation of causes; or finally, through the very nature of truth, which is determinate in the assertions that can be made on future events, as it is in all assertions, since the assertion must always be true or false in itself, even