Aspects
One planet can affect another planet through the planetary aspect. Each planet aspects another planet if they are placed in the opposition to each other.
Because of the aspects, the effect of the planets aspecting each other is combined for good or evil. The planets’ nature (malefic or benefic) and strength can be amplified or impaired by its aspects.
The signs and houses can also be affected by the aspects (even without planets in them) in the same way. Aspects from benefics will improve the affairs of the houses. Aspects from malefics will amplify the negative affairs of the house and the sign.
Except the opposition (180º aspect), Saturn, Mars and Jupiter have their own special aspects. Mars aspects 4th and 8th houses from its position in the chars; Saturn aspects 3rd and 10th houses from its position in the chart; Jupiter aspects 5th and 9th houses with its special aspects.
When a planet is placed in the same sign or in the adjacent signs between other planets, it is “hemmed in” between these planets. “Hemming in” has strong effect on the planet; it works like a major aspect. When the surrounding planets are benefics, a planet is “hemmed in between benefics”; this position will strengthen the planet and improve its nature, even if it is a natural malefic. When the surrounding planets are malefics, a planet is “hemmed in between malefics”, it will weaken and harm the planet. By the association with these malefics, the nature of the planet becomes more malefic, even if the planet is a natural benefic.