When human life lay groveling in all men's sight, crushed to the earth under the dead weight of superstition whose grim features loured menacingly upon mortals from the four quarters of the sky, a man of Greece was first to raise mortal eyes in defiance, first to stand erect and brave the challenge. Fables of the gods did not crush him, nor the lightning flash and the growling menace of the sky. Rather, they quickened his manhood, so that he, first of all men, longed to smash the constraining locks of nature's doors. The vital vigor of his mind prevailed. He ventured far out beyond the flaming ramparts of the world and voyaged in mind throughout infinity. Returning victorious, he proclaimed to us what can be and what cannot: how a limit is fixed to the power of everything and an immovable frontier post. Therefore superstition in its turn lies crushed beneath his feet, and we by his triumph are lifted level with the skies.
One thing that worries me is the fear that you may fancy yourself embarking on an impious course, setting your feet on the path of sin. Far from it. More often it is this very superstition that is the mother of sinful and impious deeds. Remember how at Aulis the altar of the Virgin Goddess was foully stained with the blood of Iphigineia by the leaders of the Greeks, the patterns of chivalry. The headband was bound about her virgin tresses and hung down evenly over both her cheeks. Suddenly, she caught sight of her father, standing sadly in front of the altar, the attendants beside him hiding the knife and her people bursting into tears when they saw her. Struck dumb with terror, she sank on her knees to the ground. Poor girl, at such a moment it did not help her that she had been first to give the name of father to a king. Raised by the hands of men, she was led trembling to the altar. Not for her the sacrament of marriage and the loud chant of Hymen. It was her fate in the very hour of marriage to fall a sinless victim to a sinful rite, slaughtered to her greater grief by a father's hand, so that a fleet might sail under happy auspices. Such are the heights of wickedness to which men are driven by superstition.
You yourself, if you surrender your judgment at any time to the blood-curdling declamations of the prophets, will want to desert our ranks. Only think what phantoms they can conjure up to overturn the tenor of your life and wreck your happiness with fear. And not without cause. For, if men saw that a term was set to their troubles, they would find strength in some way to withstand the hocus-pocus and intimidations of the prophets. As it is, they have no power of resistance, because they are haunted by the fear of eternal punishment after death. They know nothing of the nature of the spirit. Is it born, or is it implanted in us at birth? Does it perish with us, dissolved by death, or does it visit the murky depths and dreary sloughs of Hades? Or is it transplanted by divine power into other creatures, as described in the poems of our own Ennius, who first gathered on the delectable slopes of Helicon an evergreen garland destined to win renown among the nations of Italy? Ennius indeed in his immortal verses proclaims that there is also a Hell, which is peopled not by our actual spirits or bodies but only by shadowy images, ghastly pale. It is from this realm that he pictures the ghost of Homer, of unfading memory, as appearing to him, shedding salt tears and revealing the nature of the universe.
Equally vain is the suggestion that the spirit is immortal because it is shielded by life-preserving powers: or because it is unassailed by forces hostile to its survival; or because such forces, if they threaten, are somehow repelled before we are conscious of the threat. <Common sense makes it obvious that this cannot be the case:> apart from the spirit's participation in the ailments of the body, it has maladies enough of its own.  The prospect of the future torments it with fear and wearies it with worry, and past misdeeds leave the sting of remorse. Lastly, it may fall a prey to the mind's own specific afflictions, madness and amnesia, and plunge into the black waters of oblivion.
From all this it follows that death is nothing to us and no concern of ours, since the nature of the mind is now held to be mortal. In days of old, we felt no disquiet when the hosts of Carthage  poured in to battle on every side - when the whole earth, dizzied by the convulsive shock of war, reeled sickeningly under the high ethereal vault, and between realm and realm the empire of mankind by land and sea trembled in the balance. So, when we shall be no more - when the union of body and spirit that engenders us  has been disrupted - to us, who shall then be nothing, nothing by any hazard will happen any more at all. Nothing will have power to stir our senses, not though earth be fused with sea and sea with sky.
If any feeling remains in mind or spirit after it has been torn from our body, that is nothing to us, who are brought into being by the wedlock of body and spirit, conjoined and coalesced. Or even if the matter that composes us should be reassembled by time after our death and brought back into its present state - if the light of life were given to us anew  - even that contingency would still be no concern of ours once the chain of our identity had been snapped. We who are now are not concerned with ourselves in any previous existence: the sufferings of those selves do not touch us. When you look at the immeasurable extent of time gone by and the multiform movements of matter, you will readily credit that these same atoms that compose us now must many a time before have entered into the selfsame combinations as now.  But our mind cannot recall this to remembrance. For between then and now is interposed a break in life, and all the atomic motions have been wandering far astray from sentience.
As soon as your reasoning, sprung from that godlike mind, lifts up its voice to proclaim the nature of the universe, then the terrors of the mind take flight, the ramparts of the world roll apart, and I see the march of events throughout the whole of space. The majesty of the gods  is revealed and those quiet habitations, never shaken by storms or drenched by rain-clouds or defaced by white drifts of snow which a harsh frost congeals. A cloudless ether roofs them and laughs with radiance lavishly diffused. All their wants are supplied by nature, and nothing at any time cankers their peace of mind. But nowhere do I see the halls of Acheron,  though the earth is no barrier to my beholding all that passes underfoot in the space beneath. At this I am seized with a divine delight and a shuddering awe that by your power nature stands thus unveiled and made manifest in every part.
As children in blank darkness tremble and start at everything, so we in broad daylight are oppressed at times by fears as baseless as those horrors which children imagine coming upon them in the dark. This dread and darkness of the mind cannot be dispelled by the sunbeams, the shining shafts of day, but only by an understanding of the outward form and inner workings of nature.
Certainly the atoms did not post themselves purposefully in due order by an act of intelligence, nor did they stipulate what movements each should perform.  As they have been rushing everlastingly throughout all space in their myriads, undergoing a myriad changes under the disturbing impact of collisions, they have experienced every variety of movement and conjunction till they have fallen into the particular pattern by which this world of ours is constituted. This world has persisted many a long year, having once been set going in the appropriate motions. From these everything else follows.