The planes
The pivot 5
The 5 is the only number at the centre of the grid, and the only cell in direct contact with every other. Phillips treats it as the chart's pivot: the first thing a practitioner checks, because its presence or absence changes how everything else connects.
Why the 5 activates the chart
The mechanic is simple. Each corner of the grid, the 1, 3, 7, and 9, stays connected to the chart through its neighbouring cells. When those links are empty, a corner can become isolated, cut off from the rest of the chart. The 5 touches all four corners at once, so when a 5 is present, no corner can isolate. One filled cell at the centre keeps every corner in reach of the rest of the chart.
The 5 sits at the centre, the only cell touching all four corners (1, 3, 7, 9).
The 5 on the arrows
The centre is also load-bearing for the arrow system. Four of the eight arrows pass through the 5: the Soul row (2-5-8), the middle column (4-5-6), and both diagonals (1-5-9 and 3-5-7). Half of the arrows the grid can form depend on that one cell being filled.
Present, or absent
With a 5 in the chart, the corners stay connected, the centre holds, and four arrows remain possible. Phillips reads the structural effect as balance: no corner is left stranded from the rest.
Without a 5, the corners can isolate if their other links are also empty, and the four centre arrows are off the table. Phillips reads this as emotional freedom that has to be consciously developed rather than drawn on as a given. It is a different starting geometry, not a worse chart.
Where in your life do the separate parts connect, and where does something sit off on its own, waiting for a link?