HermesThe kind of intelligence of a native is shown by the relationship between Mercury and Moon. The first describes rational thinking, the latter intuitive knowledge and instinctual reactions. The difference between these two is easy to understand if you imagine a scene in the dark. You hear some loud and unknown  noises. Your rational mind (Mercury) tells you to stay calm because the noise is probably coming from an owl. No problem. Your instinctual mind (Moon) convinces you that there are no owls in in the South African bush, where are you sitting under a tree, but lions. So you run.

This makes you understand that we need both kinds of intelligences. Sometimes, fear (Moon), makes us behave right in time and helps to judge a situation correctly. Other times it might make us behave in an exaggerated manner, totally based upon sensations which might (or might be not) be reliable.

On the other side, rationality is fine, but when our rational mind decides that there might be, eventually, a percentage of danger, it might be too late…

In order to het some understand of our Mercury, we check in the chart:

  • Are Moon and Mercury in good places and do they aspect each other favorably?

This denotes a balance between rational and instinctive mind.

  • If Mercury is stronger and in commanding signs (Aries, Taurus, Gemini, Cancer, Leo and Virgo) and of long ascension (Cancer, Leo, Virgo, Libra, Scorpio, Sagittarius) and the Moon is in an obeying sign and of short ascension denotes a person in who rationality overcomes passions.
  • If the Moon is in a commanding and Mercury in an obeying sign, the person is driven by his/her passions/needs/ moods.

The aspects depend on the sign and house position and thus vary in their signification, but this helps as a quick guide

  • Conjunction: Naivete
  • Opposition: stubbornness
  • Square: intellect and fancy mixed together

You then need to consider the element, in which Mercury is located.

  • Phlegmatic signs (Cancer, Scorpio, Pisces) apprehend slowly but do have a good long time memory.

These people need to learn emotionally challenged.

  • Melancolic signs (Taurus, Virgo, Capricorn).

These depict a more practical orientation rather than a typical concept based intellect. They need to understand the practical use of what they are learning. They also do have a good long term memory.

  • Sanguine signs (Gemini, Libra, Aquarius) do apprehend quickly, but they are not steady in study because they are interested in everything. They are more attracted by concepts and ideas.They need intellectual stimulus to better apprehend. They have a good short time memory.
  • Fire signs do not much like to deepen their knowledge, but easily jump somewhat superficially from one argument to another. They need excitement in order to apprehend.

As the delineation of Mercury depends on many factors, I put them in a handy table for quick reference:

CombustThe mind is busy with superficial matters or just polite phrases.
If in an angle (especially the AC) and in own house and in any sign BUT Scorpio and Pisces (mute signs)He shows a wit apt and fit to any employment
In air sign (especially Aquarius), possibly with the nodesMost acute and witty men, speaking many languages
OccidentalA dissembler (depends also on the planet who rules place where Mercury is).
On AC and in air, swiftGood memory and understanding but the person is mutable
OrientalMore liberal nature
Over horizonOratory skills
Peregrine, in cadent house, combust, in slow motion, afflicted in partile by infortunes (esp. Mars)Corrupted wit, doltish understanding
RetrogradeStuttering, we might also consider, for example, dyslexia, a phenomena which makes a person just see a soup of letters, making it very difficult to recognize “words” in it which make any sense. In the past they have often been judged as “less intelligent”, today we know, that these people do often have a higher IQ than those called “normals or neurotypical”.
Separated from the Moon and in no aspectWeak capacity (of wit)
SwiftQuick apprehension, but inconstant, changing of opinions
Under earthArts skills
With JupiterMore honest, learned and of upright judment. Introduces humanity
With MarsMore confident and presumtuous
With MoonMor unstable
With SaturnWit more wary and the man more constant and persevering. Helps memory.
With SunAmbitous, arrogant and proud
With VenusMore eloquent and lovesome


Source: Lilly, Christian Astrology,p. 543-546