You need to ask four questions to find out how a particular Mercury retrograde is likely to play out for you:

1. Which element is Mercury retrograde in?
2. Which sign is Mercury retrograde in?
3. Which part of my chart (which House) is it retrograde in?
4. Is it triggering any of my planets? (Although this is more for student astrologers.)

While simply knowing that Mercury is retrograde is enough to warn you that things will be a little different, if you also know which element and sign it’s retrograde in, you’ll have a lot of useful information. Add to that which part of your personal chart it’s in and which planets it’s triggering, and you’ll have the full picture. You can glean all that information from this book.

To find out where and when Mercury is retrograde, you can simply keep an eye on newspaper and online columns or your Facebook feed for updates. Or if you prefer to plan ahead you can refer to the Appendix, which gives the dates of Mercury retrograde for the next 10 years.

The retrograde symbol

You might have noticed that a retrograde planet has its own special symbol () which looks like the letter R with its tail crossed by a line. Sometimes it’s written as Rx for simplicity on a keyboard, though this is just a convenient approximation. Mercury retrograde is indicated by the symbol for Mercury () followed by the retrograde symbol (). As well as being the symbol for a retrograde planet, is also the symbol for prescription, as used by doctors

and pharmacists, and comes from the Latin word recipe, meaning ‘take’.

There are theories regarding the origin of . One is that it was adapted from the symbol for Jupiter (), as an invocation to God. However, this might simply be due to printers using the Jupiter symbol in place of . Another theory is that it’s adapted from the Egyptian Eye of Horus, shown opposite.

The Eye of Horus

This symbol was used in Ancient Egypt to ward off evil, protect the king in the afterlife and for good health; there’s little evidence for this theory, although an eye has been used as a symbol for pharmacies.

The first theory – that it was adapted from the symbol for Jupiter – is most likely. A number of single letter abbreviations have been amended by adding a single stroke – for example, £ actually is a letter ‘L’ with a horizontal dash to indicate ‘pound’ (libra in Latin).