Oi. These fucking guys. They are just the absolute worst. Oh, there's a lot to love about them - If you were to pitch me the idea of a game about modern wizards where one of the factions was mad scientists who used their magic to create inventions that were scientifically impossible, I'd have approximately zero reservations about it - but because Mage is White Wolf's philosophy game, every time they come up I have to pull my hair out about the Sons' of Ether terrible take on the philosophy of science.
Tradition Book: Sons of Ether makes a valiant attempt at giving them a more coherent philosophy, and it makes the argument that they are the Mage: the Ascension universe's only true empiricists. And . . . I guess I have to accept that. They can believe things like "everything must exist, but we can filter away contradictions with a barrier of thought" and thus "nothing can wholly contradict itself," because in their dumb universe there are wizards and shit, but I guess it's one of the weaknesses of setting your game in an alternate Earth that it's sometimes hard to append the mental asterisk (*in the World of Darkness) to statements like "Because we cannot know the whole of a given phenomenon, all phenomena have potentially limitless implications."*
I could just keep going on and on about this subject. Tradition Book: Sons of Ether is just full of these little jabs like "scientific reductionism seemed designed to limit what sleepers could achieve without the Order of Reason's guiding hand," which sort of implies the opposite of what reductionism actually achieves, but I can recognize when I'm being baited. So, for the sake of amity, I'm just going to grimace slightly and acknowledge that of course the Sons of Ether are saying things like this, they're wizards, and even though they're calling their magic "Science" (the capital "S" is obligatory), at the end of the day it still operates on magical thinking.
Let's just take a moment here while I rip out half my notes and throw them in the garbage, rendering pointless any further materialist sniping on my part. The real question is "how does Tradition Book: Sons of Ether fare at delivering a useful and interesting organization of mad scientists to the WoD?"
Acceptable. The history section is weighted down a little by its framing story and a lot by WoD canon (House Golo was a mistake, IMO), but it's all interesting material. A scrappy young kid accidentally turns his hot rod into a time machine and his future self calls upon his various SoE contacts to help him navigate back through history until he can swing around and return to his native time. There's a brief detour at the apocalypse where the Sons of Ether combine their gibberish to stop a comet from destroying the Earth. It gives a good feel for the general adventure-fiction feel of the splat and makes an otherwise dry section more entertaining, but it also makes the book less generally applicable than it could otherwise be.
In the context of the Tradition Book series, it's all good. That's how these books are. They're not really players' guides to the Traditions, and they're not really GM's guides to the Traditions. They attempt to kind of be both while also being mostly about the series lore and honestly their ideal target audience is pretty much people like me - obsessive collectors and those who like to talk about White Wolf games on the internet. By that standard, Tradition Book: Sons of Ether is a B-tier supplement. Not as good as the heights of the series, but much, much . . . much better than something like Tradition Book: Hollow Ones.
The biggest point of frustration, aside from the aforementioned epistemological minefield, is that the Sons of Ether are responsible for much Mage's most memorable and distinctive setting elements. Whenever they break things down Tradition-by-Tradition and give examples of spells, magic items, spiritual realms, etc, the Sons of Ether is always a highlight. However, the magic section here is only 5 pages out of a hundred, with only two Inventions total. I think, on some level, I would have preferred a second volume of Technomancer's Toybox. The revelation that you can make antimatter with Sphere magic is a total game-changer, though. The Sons of Ether are now officially the most dangerous people on the planet.
Overall, I'd classify this book as an essential piece of my library, but not necessarily the first one I'd reach for when making a Mage character. It sells the pulp aesthetic and "scientific" idealism of the faction and offers some interesting character ideas, but going into their philosophy and trying to justify their paradigm probably weakened the Tradition more than it helped. Just give me mad scientists with baroque inventions and nonsense theories. That's all I need.
Ukss Contribution: They're not just pseudo-scientists when it comes to physics and chemistry. They make a hash out of archaeology and paleontology too. According to their theories, the Earth was once ruled by a civilization of violent flightless birds. I'm picturing a land of scarred Chocobos who will kick you to death if you look at them the wrong way.