The private side of the vertical axis
The fourth and tenth houses form a useful comparison between private foundations and visible responsibilities. The fourth can describe a dwelling, ancestry, property, or what a person experiences as a base. William Lilly’s seventeenth-century house list assigns lands, houses, fathers, and the end of a matter to this place in the context of horary practice. A modern natal question may instead ask where someone feels settled or what family history they carry. These are different applications of an old house vocabulary; neither lets a chart establish the factual condition of a home without ordinary evidence.
The IC and fourth-house boundary
The IC is the ecliptic intersection with the lower half of the local meridian and is opposite the Midheaven. In many quadrant systems it is the fourth cusp. In Whole Sign or Equal houses, it can sit inside a different numbered house. The fourth house remains the fourth sign or thirty-degree division from the Ascendant under those methods. A chart can therefore give an IC sign and a fourth-house sign that differ. State which coordinate is being discussed before treating “IC” and “fourth house” as the same placement.
A concrete reading order
Locate the fourth-house span and record its sign or cusp, then identify any planets inside it. Read those planets by their own signs and aspects before assigning a household story. A planet at the edge of the fourth deserves a boundary check, especially when the recorded birth time is rounded to an hour or the birthplace offset is uncertain. Compare the tenth house to see how the private/public axis is organized in the chosen system. This is a way to pose questions about home and work, not a mechanism for inferring a person’s address or parental history.
Parents are not a universal assignment
Older authors often assign one parent to the fourth and the other to the tenth, but the parent chosen for each house changes among traditions. Gendered formulas from a historical text should not be silently treated as a rule for every family. The fourth can be a useful entry to discuss belonging or inherited conditions while the actual family structure comes from the person, not the chart. Without a reliable birth time, neither the fourth cusp nor the IC can be stated confidently.
Am I reading the fourth-house span or the exact IC degree?