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Welcome to Episode One Hundred Thirty-One of Lucretius Today. This is a podcast dedicated to the poet Lucretius, who wrote "On The Nature of Things," the only complete presentation of Epicurean philosophy left to us from the ancient world. I am your host Cassius, and together with our panelists from the EpicureanFriends.com forum, we'll walk you through the ancient Epicurean texts, and we'll discuss how Epicurean philosophy can apply to you today. We encourage you to study Epicurus for yourself, and we suggest the best place to start is the book "Epicurus and His Philosophy" by Canadian professor Norman DeWitt.

If you find the Epicurean worldview attractive, we invite you to join us in the study of Epicurus at EpicureanFriends.com, where you will find a discussion thread for each of our podcast episodes and many other topics.

Today we continue Epicurus' Letter to Pythocles and we look at the implications of the Epicurean position on certain weather phenomena. Now let's join Joshua reading today's text:

BAILEY:

[99] Signs of the weather may occur owing to the coincidence of occasions, as happens with animals we can all see on earth, and also through alterations and changes in the atmosphere. For both these are in accordance with phenomena. But under what circumstances the cause is produced by this or that, we cannot perceive.

Clouds may be produced and formed both by the condensation of the atmosphere owing to compression by winds and by the interlacing of atoms clinging to one another and suitable for producing this result, and again by the gathering of streams from earth and the waters: and there are several other ways in which the formation of such things may not impossibly be brought about.

[100] And from them again rain may be produced if they are squeezed in one part or changed in another, or again by a downward current of wind moving through the atmosphere from appropriate places, a more violent shower being produced from certain conglomerations of atoms suited to create such downfalls.

Thunder may be produced by the rushing about of wind in the hollows of the clouds, as happens in vessels on earth, or by the reverberation of fire filled with wind inside them, or by the rending and tearing of clouds, or by the friction and bursting of clouds when they have been congealed into a form like ice: phenomena demand that we should say that this department of celestial events, just like them all, may be caused in several ways.

[101] And lightnings too are produced in several ways: for both owing to the friction and collision of clouds a conformation of atoms which produces fire slips out and gives birth to the lightning, and owing to wind bodies which give rise to this flash are dashed from the clouds: or compression may be the cause, when clouds are squeezed either by one another or by the wind. Or again it may be that the light scattered abroad from the heavenly bodies is taken in by the clouds, and then is driven together by the movement of the clouds and wind, and falls out through the clouds; or else light composed of most subtle particles may filter through the clouds, whereby the clouds may be set on fire by the flame and thunder produced by the movement of the fire.

[102] Or the wind may be fired owing to the strain of motion and its violent rotation, or clouds may be rent by wind and atoms fall out which produce fire and cause the appearance of lightning. And several other methods may easily be observed, if one clings always to phenomena and can compare what is akin to these things. Lightning precedes thunder in such a conformation of the clouds, either because at the moment when the wind dashes in, the formation of atoms which gives rise to lightning is driven out, but afterwards the wind whirls about and produces the reverberation; or because they both dash out at the same moment, but lightning moves at a higher speed towards us, and thunder comes after, as in the case of some things seen at a distance and producing blows.

[103] Thunderbolts may occur because there are frequent gatherings of wind, which whirls about and is fanned into a fierce flame, and then a portion of it breaks off and rushes violently on the places beneath, the breaking taking place because the regions approached are successively denser owing to the condensation of clouds, or as the result of the actual outburst of the whirling fire, in the same way that thunder may be produced, when the fire becomes too great and is too violently fanned by wind and so breaks through the cloud, because it cannot retreat to the next regions owing to the constant condensation of clouds one on the other.

[104] And thunderbolts may be produced in other ways too. Only superstition must be excluded, as it will, if one successfully follows the lead of seen phenomena to gain indications about the invisible.

Cyclones may be produced either by the driving down of a cloud into the regions below in the form of a pillar, because it is pushed by the wind gathered inside it and is driven on by the violence of the wind, while at the same time the wind outside impels it sideways; or by wind forming into circular motion, while mist is simultaneously thrust down from above; or when a great rush of wind takes place and cannot pass through sideways owing to the surrounding condensation of the atmosphere.

[105] And when the spout is let down on to the land, whirlwinds are produced in all the various ways in which their creation may occur owing to the movement of the wind, but if it reaches the sea it produces waterspouts.