The news is constantly full of "investment themes" -- BRIC, commodities, falling Dollar, alternative energy, mortgage crisis, and so on.

Investing with themes is a good idea, because you will be swimming with the stream instead of against it. However, themes don't last forever.

Getting onto a theme too early can be costly in terms of losses or "dead money". Getting in too late can result in underwhelming profits or even losses, if everybody else is exiting when you are entering.

Whatever theme you may be contemplating, we think it is useful to analyze it in terms of generic theme dimensions. From our perspective, those dimesions are:

• Development Time

• Strength

• Duration.

Properly classifying themes will help you decide if they are right for you. For example, a fast development, weak and short duration theme is suitable only for the nimble -- essentially short-term traders. On the other hand a slow development, strong and long duration theme is not really suitable for a trader, but may be suitable for a long-term investor in an asset allocation program. There are many degrees between those two extremes.

To help you with classification, we have developed this three-dimensional chart that creates 27 theme categories: