Seneca’s Natural Questions (Quaestiones Naturales) is an oddity of philosophical literature. It does not fit into any neatly defined category, and stands nearly alone in its blend of science and speculative philosophy. Perhaps “science” is not quite the correct word. Our philosopher makes no experiments, and attempts no generalized scientific conclusions. He is more concerned with describing and classifying the bewildering variety of natural phenomena that was seen and experienced by man, than in using experimentation to promote the advancement of learning. The Romans were not scientists.
He presents us with a survey of the natural phenomena in earth and sky. By analogy he tries to demonstrate which theories of his day are wrong, and which are not.
But Seneca is clear on his purpose: the reason to study Nature is for our moral improvement. His primary concern is to moralize. What a marvelous idea! And what scientist of today, in our negligently non-judgmental era, would dare suggest such a purpose?
How does the study of Nature help my moral development? The answer, Seneca tells us, is that the study of Nature’s workings confirms the fundamental tenets of Stoicism. The world moves on; death can come at any time; it is better for us to face our lives with diligence and quiet courage.
Perhaps, in so asking this question, we begin to approach the source of our modern problems in educating and training the youth. “What is most important in human affairs?” he asks. Not material gain or glory, but “Rather to have seen all the Cosmos in your mind and–for no victory is greater–to have conquered your vices.” 
In book one, he covers atmospheric phenomena: rainbows, halos, parhelia, meteors, and comets. Book two describes in detail lightning and thunder. And here is where Seneca shows us why he is a philosopher. Not content just to describe these things, he philosophizes about them. So he interrupts his discussion of lightning to discuss the meaning of Fate, and how it is revealed by omens. He reminds us that we should never fear extreme phenomena of weather, since death is unavoidable. Death will come whether we want it or not: so why fret about thunder or lightning?
Book three deals with the earth’s various types of waters and water cycles; book five, winds and tempests; book six, earthquakes; book seven, comets and associated meteorological phenomena. It is a strange and wonderful book, in which every opportunity is taken to digress for our moral edification. So Seneca interrupts a discussion of the earth’s wind patterns to rue that we immorally exploit the earth’s winds to construct murderous warships.
I love this little book. He rises to great eloquence in many passages, among them this passionate plea:
With this, my dear Lucilius, we wrap up our discussion of these causes [of earthquakes]. Now we turn to those things which pertain to the solace of the spirit. It is better for us to be morally strong than to be learned. One does not happen without the others. Strength does not come to the spirit except by the study of good arts, and by the contemplation of Nature….Why should I fear a wild animal, or why should I tremble at the light of an arrow or spear? Greater dangers are waiting for me: lightning, earthquakes, and the entire apparatus of Nature…A man’s life is an insignificant thing, but contempt for mortal life is a great thing. 
To the ancients, character and moral development was more important than being “factually correct” in everything. If you must know one thing about ancient literature, know this. We see this tendency in historiography of the period, as well as in works of geography and science. It is us moderns who are preoccupied with technology, truth, and always “being right.” We may be better off now, with out technology and our theories, but have we advanced morally? I am not so sure.
We can learn something from these old books, if only we will listen.
 Quid praecipuum in rebus humanis est?…sed animo omne vidisse et, qua maior nulla victoria est, vitia domuisse. (III.10).
 Haec, Lucili, virorum optime, quantum ad ipsas causas; illa nunc quae ad confirmationem animorum pertinent. Quos magis refert nostra fortiores fieri quam doctiores. Sed alterum sine altero non fit; non enim aliunde animo venit robur quam a bonis artibus, quam a contemplatione naturae…Quid est enim cur ego hominem aut feram, quid est cur sagittam aut lanceam tremam? Maiora me pericula expectant; fulminibus et terris et magnis naturae apparatibus petimur…Pusilla res est hominis anima, sed ingens res contemptus animae. (VI.4).
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