The sign of Mars says HOW you fight; the house says WHERE your force is spent. They are two different questions, and the second is almost never asked. Mars in Capricorn describes somebody who acts with method and does not give up; Mars in Capricorn in the 6th house describes that same force turning into a tireless worker, and in the 7th it describes the same person negotiating hard with the one she loves. It is another life, with the same sign.

Here the series changes its rule, and it is worth noticing. The house of Mercury and that of Venus are almost always the Sun's or a neighbour of it, because both walk tied to it. Mars is tied to nothing: it can fall in any of the twelve houses, including the one opposite the Sun. That is why this is the reading that most explains what the Sun sign was not explaining.

And there is one thing the house of Mars says that no other says: that is where you have a scar. Mars is the planet of the cut, the accident, the surgery and the fight, its house tends to mark the area of life in which the person got hurt, defended herself and learned to fight. It is not an omen, and it should not be read as a warning: it is where the biography already has a history.

And the hard difference of this series has to be said before anything else: the house depends on the exact time of birth. The whole chart turns about one degree every four minutes, and a house boundary passes in around two hours. Whoever guesses the time does not get an approximate reading, they get somebody else's reading.

Having Mars in the 10th house means your ambition is visible and your fight is public. The 10th house is the career, the reputation, the authority, what others know of you without knowing you. Mars there puts the force in the place everybody sees. This person wants to arrive, and hides it less well than she thinks she does.

It is a placement of natural command: she takes charge, decides and puts up with the unpopularity that comes with it. It is also the one who collides with the boss, enters a dispute over a post and builds a reputation as a difficult person that is almost always unfair and never gratuitous.

And here is what hardly any text writes down: the scar of this placement is public, and it usually has a witness. A humiliating dismissal, a criticism in a meeting, a mistake everybody saw. What stayed was not shame: it was vigilance. The person reacts fast to anything that looks like diminishing her in public, and sometimes reacts to somebody who was diminishing nothing.

There is a second piece that changes everything: which sign that Mars is in, the way that force is spent in this area. Mars in the 10th house in Capricorn builds step by step and skips none; in Aries, it wants the post now and fights for it in front of everybody. The house says WHERE; the sign says HOW.

It shows in how much energy this person spends on her own place in the world. These are concrete signs, the kind you recognise in your own week:

• takes command with nobody asking, and does it well
• has already fought with a boss, and does not regret all of it
• works too hard when the post is at stake
• reacts strongly to criticism made in front of others
• has a reputation for being difficult, and it is partly deserved
• cannot work for somebody she does not respect

Notice what this list does not say. It does not say the person is arrogant or a careerist, two labels this placement carries and which describe the excess, not the placement. It says her force is spent on public ground.

The strength is command: this person can bear being responsible. She decides when nobody wants to decide and takes the blame when the decision goes wrong, and since most organisations are made of people running from both of those, whoever does both rises, even without charm.

In practice that turns into three useful things: an ability to lead that appears by itself in any group; a resistance to unpopularity that allows deciding rightly instead of deciding prettily; and a declared ambition, which opens doors that modesty keeps shut.

That strength does best in leadership, her own venture, a competitive career, a large undertaking, politics and any arrangement with responsibility and a name on the door. And it does badly in a post with no autonomy, with a boss she does not respect and anywhere ambition is treated as a character flaw.

There are two, and they are opposites: the excess is ambition turning into running people over, and the deficiency is somebody who switched the engine off precisely in this area of life. The Shelly Method reads every archetype through four faces, the light, the shadow, the excess and the deficiency, and it is the last of them that hardly any text mentions.

The excess is going over the top of people: the person decides alone, ignores whoever knew more and then finds she won the post and lost the team. It also shows up as a career that turned into an identity, and then every professional criticism is lived as a personal attack, with a reaction others find disproportionate and she finds fair.

The deficiency is the opposite and goes unnoticed for years: the person stopped reacting here, and calls that patience. Here she is the person who gave up disputing in public. After a visible fall, she stopped applying, stopped asking, started doing the work and disappearing, and watches less prepared people take the place that was hers. It is the most expensive loss of this placement, because the force does not vanish: it turns into resentment.

Both faces have the same raw material, and that is why the repair is the same: an ambition that needs people alongside, and not less will. It is not solved by asking the person to be humble, the will to arrive is legitimate and it is the engine. It is solved by taking somebody along: every step climbed with one more person costs half and lasts twice as long, and that is what the sign of Mars and the rest of the chart show.

Every house has a pair, and the pair of 10 is house 4. They are not separate themes: they are the two ends of the same pair, and the excess in one shows up as a lack in the other. The 4th house is the opposite: the home, the family, what nobody sees. A Mars in the 10th much spent outside usually gets home with nothing, and this person's private life is far poorer than the career suggests.

The correction is not to work less: it is to give the home the same seriousness of scheduling given to work. The 4th house is the only one that goes on existing when the career changes.

It matures when the person discovers that authority and a post are different things, and that distinction is worth more than any attempt to learn not to want to rise. Command stays the talent; what changes is that it stops costing the people.

There are two rhythms that help to understand the arc, and both belong to Mars itself: the return, every two years, which turns the cycle of this house and calls for a fresh start; and the retrogradation, every twenty-six months, for some nine weeks. In those weeks the subject of this house tends to ask for review, and here they usually bring a review of a contract, of a partnership and of the career itself. It is a good moment to rethink the direction, and a bad moment to resign in the heat of the moment.

Maturity here is not learning to settle for little. It is the person coming to distinguish the dispute that builds from the dispute that only marks a position. A mature Mars in the 10th house goes on wanting to arrive, and comes not to arrive alone, and it is that company that turns ambition into authority.

No honest text gives an age for this. The arc depends on the whole chart and on the life the person had.

It says where your force is spent, and not whether you will win the fight. The house is the address; the result is your life.

Which sign that Mars is in changes the whole manner: Mars in the 10th house in Pisces leads by welcoming and is underestimated until the day it is not; in Scorpio, it builds real power away from the spotlight. See the series Mars in the 12 signs.

And your Sun does not help you guess this house, unlike what happens with Mercury and Venus: Mars falls in any of the twelve. The other half of the pair is Venus, she shows what attracts, and Mars, what gets done about it. See the series Venus in the 12 houses.

One limit said out loud, because it is part of reading seriously: none of this is prediction. Astrology describes a tendency and gives vocabulary for what the person already lives; it does not announce an accident, does not promise victory and does not replace your own decision.

And the questions that come up most on this subject, with the short answer: