2. The Golden Age: Securing Mind-Tools / Practicality.
3. ? Magic. The Way.?
4. ? Myth. Knowledge.?
The above ages are differentiated from conventional views of aging, of course, because these 'ages' are supposed to lead to eternal youth. As I say in my book, I have only discovered the first or second age, and that's good, if it turns out they are really ages of conventional age...
But there is much more information in the book which is definitely useful.
You can get the intuition that the "Golden Age" is the age of acquiring tools for becoming immortal... through a principle which is already acquired in the 'first age'.
Depending on how temporal the original world is, the ages may occur rather quickly at first, and then become extended...
It is also possible to reinstate earlier schema later, and do a re-determination (this is how one really returns to the First Age)...
If you are looking for books on immortality, I have published two, which are really more useful than the above description belies:
The Dimensional Immortality Toolkit (Recommended. I have been perusing it recently, even though I wrote it myself...)
The Secret Principles of Immortality. (An earlier work, if you prefer)