The first aspect is to nail the concept of how to express passages
of time.

For example, by saying "In the First Age...".

Or, "After an uncertain number of years..."

These initial decisions provide structure for the system of

For example, if X happens in the First Age, one can apply a
theory such as evolution, transcendentalism, cultural
degeneration, etc. to reach Y in the Second Age. If one can
predict the same pattern, then one can predict Z in the Third Age,
or U in the Fourth Age, etc.

However, if the theory of prophecy is wrong, the prediction will
also be wrong.

Therefore, it is important for the theory of prophecy to fit one of
the following criteria:

1. The results follow logically.
2. The theory is sufficiently vague that it remains probable. This
can be helped by working with existing information.
3. The prediction is psychic. See Psychic Prediction.
4. The prediction works with classical knowledge of history,  
psychology, theology, or politics such as knowledge of the gods or
bodies of immortal literature.