The first house is the most personal point of the chart. This represents the physical body and the incarnation for this lifetime. It represents the beginning of life and is known by the Greeks as ‘The Horoscope’. In traditional and horary astrology the first house always represents the subject of the reading. Mercury finds its joy here. The zodiac sign Aries is the co-significator for this house.
“It hath signification of the life of man, of the stature, colour, complexion, form and shape of him that propounds the Question. It signifieth the common people, or general state of that Kingdom where the figure is erected. And as it is the first house, it represents the head and face of man”
“The house is masculine. The cosignificators of this house are Aries and Saturn; for as this house is the first house, so is Aries the first sign, and Saturn the first of the planets, and therefore when Saturn is but moderately well fortified in this house…. promises a good sober constitution of body, and usually long life.
Mercury doth also joy in this house, because it represents the head, and he the tongue, fancy and memory: When he is well dignified and posited in this house, he produceth good orators: It is called the Ascendant, because when the Sun commeth to the cusp of this house, he ascends, or then ariseth, and is visible in our horizon.”William Lilly