This book was rather a disappointment. It contains about 280 pages, of which 15 pages are forewords, 80 pages are introduction (which is rather informative, to be honest) and 60 pages or so notes and bibliography. Usually I don't state things so precise - pedantic isn't my style - but a simple arithmetical operation (i.e. addition) leads to the conclusion that the real work spans 125 pages.
Next, this 'real work' is comprised of some fragments of Diogenes Laertius' description of Epicurus as a person and his works, three letters of Epicurus to others (of which at least two are questionable in origin), a summary of his doctrines (originating from Laertius' descriptions) and a lost piece of fragments that was dug up from the Vatican archives in the nineteenth century. Of these 'works' the letters comprise the biggest part of the book, but about half of the letters is comprised of parallel passages in later Epicurean Lucretius' De Rerum Natura (On the Nature of Things). Why? The editor claims these passages of Lucretius are included to contrast styles - both works deal essentially with the same topics, but where Epicurus writes in a dry and unimaginative prose, Lucretius writes in a splendid poetic fashion.
That's all well, but it effectually means that one buys a book on Epicurus for a standard prize, which then contains only about 50 pages or so on Epicurus - and 230+ pages (!) not on him. It makes the book rather a disappointment.
But the disappointment has another dimension. After reading the introduction, one knows already what's in store - there's no added value whatsoever in reading the original passages. The splendid introduction has already explained all there is to know about Epicureanism - it's development from both Democritus' atomism and the Cyrenaic hedonism running rampant in Athens at the time; the crucial additions which Epicurus made to amend the problems of atomistic materialisml; and the intricate relationship between physics, epistemology, ethics and religion.
In short, Epicurus claims everything in the universe consists of matter in motion and empy space. All processes, including human sensation, perception and idea formation have to be explained in mechanistic terms. In such a universe everything is caused by the coming together and falling apart of atoms in atomic configurations, so there is no room for creative gods. Due to the atomic swerve - a random movement of atoms which allows for soul-atoms to be non-determined - there is room for free will, according to Epicurus.
This physical nature of the universe means that sensation and perception have to be explained in mechanistic terms as well. Objects give off flows of atomic films, which constitute certain qualities. These films hit our sensual apparatus and are there transformed into ideal (perceptual) representations in the mind. This has implications for Epicurus' theory of knowledge: our senses simply relay clear and distinct information, this sense data is literally 'true' and all there is. Falsity consists in us imposing our own expectations and beliefs on the raw sense data that streams into our perception - we are distorting true information and subsequently conclude that our senses perceive us (à la Parmenides and Plato). This makes Epicurus an empiricist avant la lettre (one immediately sees the inspiration Locke, Berkeley and Hume drew from this theory of knowledge).
There is another implication: it seems that mechanistic explanations explain not only the workings of sense experience, but - more importantly - the interaction of soul and body. Our soul consists of atoms as well, and gathers knowledge through experience, meaning that, in ultimo, our soul is materialistic as well. According to Epicurus, our soul consists of the most perfect, spherical atoms. But anything material is only temporary, so when we die, our soul disintegrates just like our physical body. And this means there's no afterlife.
And this connects Epicurus' atomistic materialism intimately with his ethics and his religious stance. According to him, since body and soul are materialistic, they perish after death. And this means that we only experience things - most importantly pleasure and pain - when alive. And this means that death does not affect us in any way. So our fear of death, as well as our fear of an afterlife, is nonsensical. Add to this the non-existence of contemporary Greek gods - who created the universe and punish us after death, both being impossible in an Epicurean universe - and there is no fear of hell either.
And the realization of the uselessness of our fear of death, afterlife and divine punishment is the first step on the path to leading a good life. It is a negative step, in the sense that it cuts away senseless superstition and myth from our lives. The next step is the positive aspect: live life according to the pleasure-principle - pleasure is good, pain is bad - 'good' and 'bad' being both psychological and moral terms here. We should strive to avoid pain and experience pleasure.
And it's here that the common perception of Epicurus flies off the road. Most people associate Epicurus with a hedonistic lifestyle, but the truth is, he was rather much more nuanced than this. For starters, Epicurus includes time as a factor in his ethics - which means that short-term pleasure can cause long-term pain (eating, drinking, having sex, etc. etc.), while short-term pain can cause long-term happiness (undergoing surgery, abstaining from pleasures, etc. etc.). And this leaves 'reason' as a determining factor to decide which action is best, for me, in the current situation I'm in. Epicurus' ethics is highly relativistic - in terms of person, time and place - as well as highly ascetic. The most important thing to realize in life is the worthlessness of aiming at wealth, honour or even a decent social life - a truly happy person tames his desires, cultivates his needs to the bare minimum and only socializes with a couple of intimate friends.
This is not what most people associate with Epicurus, but this is how the man actually lived his life. It is reported he lived off water and bread, and the most extravagant thing he ever asked for was some type of Greek cheese, which he could then munch on on special occassions. He also reportedly swore off sex and lived for study and contemplation. Above his garden, there supposedly hung a sign which said: "Have you not been well entertained? This garden does not whet your appetite, but quenches it" - which illustrates most beautifully Epicurus' ethics (nevermind what later thinkers made of it).
And in a sense, it's only logical that he reached this conclusion. If you truly believe the world is fully deterministic and only comprised of matter in motion through empty space, all passions are caused mechanically as well. And this means that they are nothing but atoms in motion, so resistable. At least, if you subscribe to his notion of free will - and this is the problematic part in Epicurus' ethics (as far as I can tell). He claims the atomic swerve introduces a certain random motion of atoms in an otherwise determined universe, but how is this helping him 'producing' free will in our soul? Our soul is nothing but configurations of spherical atoms, which are either determined through natural laws or determined through random events taking place. Either way our soul is determined.
(This reminds one of the modern debate on free will, in which certain people, some very learned like Sir Roger Penrose, claim that quantum indeterminacy at the sub-atomic level leads to human brains being not determined by natural laws. But in this case our brains would be determined by random quantum fluctuations, meaning that what we feel, want and do is nothing but randomness - not free will.)
Anyway, I already went to far in my anachronistic explanations of Epicurus' mechanistic explanations. Of course the Greeks in the second century B.C. had a totally different lens (or rather: lenses) with which to view the world. It's just, Epicurus ethics are rather plain and uninformative; his physics is totally obsolete; his epistemology has been clarified and expanded by much better thinkers and (!) writers like Locke, Berkely and Hume; and his views on religion, being nothing but superstition and myth, are time capsules of Athens during second century B.C.
To conclude: the book itself is a big let-down, the writing of Epicurs offer nothing spectacular, and the ideas are only interesting from a historical perspective. I can't recommend this book to anyone.
I'd like to make a last remark, though. Epicurus tried to explain everything in terms of matter in motion through empty space, and offered a multiplicity of explanations for natural phenomena. In this he cleary fought against Plato and his followers, who'd fled into an imaginary world of Forms and thought this explained everything. The problem for Epicurus was the intimate connection between his view on nature and theory of knowledge on the one hand, and ethics and religion on the other hand. For millennia, the name of Epicurus (as well as Lucretius) would sound the alarm of unbelief (and rightly so) in monasteries and universities all over Europe. It is only in the Renaissance that original works were translated and opened up to European scholars; and it was only in the seventeenth century (starting with Gassendi) that the atomistic materialism of Epicurus started to replace Aristotle's framework as the metaphysic of the world. Ever since, we (still) think of the universe, and everything in it, in terms of material particles in motion, and this worldview has led to so much progress - on all accounts - that it is hard to grasp why the Greeks didn't take this route...
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I'd like to add a second 'final' remark. Epicurus (and more so Lucretius) is often seen as an atheist and materialist, in the sense that Karl Marx is often viewed by religious people. Or a more modern thinker like Richard Dawkins. This is, frankly, untrue. Epicurus states that there are gods, just not the contemporary Greek gods. The contemporary religion was the story of anthropomophic gods, who created the world and each other, but also were having sex with family members and spouses of other divinities, required human sacrifices (sometimes literally), and were continuously fighting each other to death. This is delusional, according to Epicurus. He sees all of this as wishful thinking, and destructive of human happiness. We are projecting our own fears of death and the afterlife and creating these gods - as some sort of therapeutic alleviation (a Freudian avant la lettre?!).
Epicurus claims gods exist, just not in the conception that humans normally think of them. They exist in interstellar space; are perfect and hence not active (since action is a move towards a better state, i.e. a recognition of imperfection); are eternally occupied with contemplating on themselves as perfect beings (à la Aristotle); and are in no way concerned with nor receptive to human desires and feelings.
When judging such historically situated claims, it is always hard to distinguish between an author's true feelings and his pampering to contemporary feelings, in order to avoid bad things happining to him/her. In this particular case, it is hard to determine what would have happened had Epicurus claimed he was an atheist - Socrates had earlier been killed due to unbelief and stirring up youth - and Epicurus' times were much more of a turmoil. But I think words of a historical figure should be interpreted as genuine first, and be doubted if valid reasons emerge. I can't find genuine reasons to doubt Epicurus was not an atheist, so I'd conclude he wasn't.