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I can?t imagine why someone would associate cars with the 1st house ? There?s a valid argument for the 2nd and the 3rd: the 2nd house because that governs our moveable possessions and your car would be a possession and hopefully moveable :) The third house generally signifies transport issues though, so if the question was ?will this be a good car to buy?? I would take the primary signification from the 2nd house because I would be viewing the car as an item that is being evaluated in terms of how good it will be as a personal possession and investment of my funds (that is, a good buy or a bad buy), but I would also be very wary of afflictions to the 3rd house because that would be warning of problems concerning the car?s ability to travel. Other people might do it the other way around but really both of these houses need to be considered if you are considering a financial implication. But if the question was ?will the car make the journey?? the 3rd house would be more naturally relevant than the 2nd.

In every chart you have to think through what the essential issue is and then assign house rulerships accordingly. That?s why there are a lot of things or circumstances that could easily fall under the remit of more than one house and just following other people?s lists or instructions can leave you missing the mark.

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Thanks Deb. :' The use of the first house as significator for a car is by Lee Lehman in her book, "The Martial Art of Horary Astrology". She justifies this by referring to Lilly's use of the first house for questions about ships. As ships were vessels of transportation, she's "extrapolated" this use to fit modern methods of transportation.
Thanks for your reply. :)
H.