Personally, I follow out of sign aspects. They are often relevant in horary and I have Mars in Aries in the 10th square Jupiter in Leo and I see this aspect being true, although I suppose its energies could be explained in other ways. The fact that Venus is within 5 degrees of the next sign is itself an unstable placement and means it takes on the energies of both Libra and Scorpio also, according to Bonatti. My Jupiter is on the cusp of Cancer and I relate to both Jupiter in Cancer and in Leo (and in Vedic it is in Cancer). By being the ascendant lord, this could suggest someone who is indecisive, changeful and maybe even changes their own appearance frequently, in spite of a fixed Taurus rising.
I am not sure if I am reading the chart correctly, but Venus is "above" Saturn in their square aspect? As in, this is a dexter square aspect from Saturn to Venus? Maternus says that Venus above Saturn in a square indicates respectable wives, but both spouses will dissimulate their affection, while Saturn above Venus indicates bitter experiences with women.
Venus is looking backwards from Libra towards Aquarius, making this a sinister aspect. If it were aspecting Saturn in Leo it would be dexter, for example. In this aspect Venus would be said to dominate but that is kind of irrelevant in my opinion since she is under the influence of an angular strong superior who receives her. Planets that are received by a dignified planet that is stronger than them are often influenced by that planet. I would say Saturn holds not only an influence over the career but also the personality, appearance and health, etc (things of the 1st house).
Saturn in the 10th can show becoming successful after a lot of hard work, climbing your way to the top after mastering something, and your chart shows a little similarity to Howard Hughes's, who also had interest in technology. However, I think one of the reasons he was so successful was also his Pluto in the 1st. Saturn is generally more positive in the 10th when it is dignified like in your chart. When in poor dignity, it can show reaching a high position but then having a fall from grace and possible ruin, such as in Hitler's chart.
Often the 2nd house can have influence over career and help describe it and yours is also ruled by Mercury, suggesting something that uses intelligence, communications, writing, etc., and in Sagittarius that could include more broad topics, especially with Mercury square Jupiter, which is not the best placement for a specialist - the small details can be glossed over. To me this would seem more difficult for the computer sciences because you might be more interested in more broad ideas rather than the fine details that it would entail -you might find that boring. Jupiter is a superior and they are more interested in bigger ideas, even though they may understand many concepts (knowing the ins and outs of everything might not suit them though).
I don't necessarily view Mercury under the beams or combust as prone towards lying. Sometimes the person can be more private or just in general holds a lot of pride in their intellect. In Sagittarius I would say Mercury is also overly hot by being in a day chart, with the Sun and in a fire sign, so the intellect can go one of two ways: it might show lack of attention due to getting bored or losing focus, or it might be sharper and maybe even a genius at understanding certain subjects in some cases - information comes quickly. It depends also on how swift Mercury is and what it aspects - here it holds the light of Jupiter, although both in detriment they are in mutual reception, suggesting some superior intellect. Mercury is always within a few signs of the Sun and is often combust. It is a common aspect. However, Mercury is a trickster planet and when in detriment and in the 8th, that might suggest some dishonesty. With the Jupiter square and influencing Mercury (and in mutual reception), my guess is you more so promise more than you can do rather than lie on purpose. You may not realize you break your promises or don't place much importance in keeping promises. This is a placement that is sometimes seen in the charts of salesman because they are good at making an idea sound good to someone but don't always follow through on those promises. You mentioned the idea of sales and in the 8th this is a pretty good signature placement of a salesman, so I wouldn't be surprised if you did work in that field or used salesman tactics in your career. I have the aspect as well and I am a bit guilty of talking people into doing things fairly easily, or writing in ways that are persuasive, but I am not a salesman (but I also have Mercury applying to trine Saturn, which is rather different). Some might say Mars in the 8th could gain through losses for others and can sometimes show dishonest things like tax evasion, etc. but you have enough dignified planets in your chart that seem like they might help control more negative energies. If you are aware of any negative tenancies to take advantage of others, hopefully you will correct that behavior.
Regarding aspects between the 10th ruler and the ASC ruler, my guess is that Firmicus would also take into consideration whether or not the 10th ruler beholds the ascendant and here it would via square, but it also is able to see Venus by sign, since they are in the same element. I would personally regard the square between Venus and Saturn but it wouldn't be as strong as one that was in the correct sign placement. Still, since Libra is a sign of long ascension, a square from that sign is viewed more so as a trine and Saturn would receive Venus via exaltation and is itself dignified, so it is not as difficult as it could be.
The idea of a planet aspecting a house or its lord is in general important in traditional astrology. I personally would rather see the ascendant ruler behold the ascendant than the 10th house because that means the person has a better handle on their own life rather than working against themselves. Still, a dignified ruler as the lord of the 1st can be good at being in control of their life (if not afflicted).
The 2nd ruler in the 8th seems like a strong indication of income through the finances of other people, such as in working in sales or finances. While you do have indications that suggest interest in technology, it seems like your career focus would be more so in something else and will likely involve a partnership of some sort, since Mars is ruler of the 7th and is in the 8th and aspecting the 10th ruler. Pluto in the 7th further emphasizes some joint finances. It could even be that your future wife/romantic partner is your business partner also and with Pluto in the 7th house, they could be a powerful person in business but Pluto in the 7th can also be a warning to be careful of who you trust and often those who have this have trust issues for a reason. Often there is at least one major relationship (not necessarily a romantic one) where trust is broken beyond repair and it shapes the way you view the world, since the 7th deals with how we view others in general. Scorpio on the 7th cusp and Pluto in the 7th suggests at least one long term relationship but relationships are unlikely to be easy for you. I don't see indications of an older romantic partner but they are likely to be aggressive, outspoken and probably have a dark complexion/hair. Since Mars is in Sagittarius, they could be a foreigner or have a different background than yours. I am guessing you will also have children, even though your 5th is in Virgo, a barren sign. I rarely see someone with Jupiter in the 5th, even in Virgo, who ends up childless and Moon in Scorpio is a pretty fruitful placement as well.
I don't like Placidus or Whole Sign, so we are all in disagreement here. Hahaa. Even if Saturn is in the 9th, it still lords over the 10th and is elevated.
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