One change, with everything else held fixed
Create the demonstration chart for 28 July 1990 with The Sun, The Star and Strength. Then replace only the first card with The Tower. This is a controlled comparison of the calculator’s rules, not an experiment showing that tarot changes a person’s life. Both versions use identical natal positions, transit samples and Saturn-return ages.
The first card belongs to the formative phase. It cannot move Jupiter or Saturn, alter your Sun sign or change the date of a sampled aspect. If a reading gives that impression, separate the astronomical calculation from the symbolic description. In our model, the card changes the baseline and the wick extension, while the transit contribution stays fixed.
The expected difference before any clipping
The Sun’s tone is +0.9 and The Tower’s is −0.7. Multiplying the difference of −1.6 by the baseline multiplier 15 gives −24 points. Away from a phase transition, the raw formative score therefore falls by exactly 24. The displayed difference can be smaller if either result reaches the 8–96 limits; integer rounding also matters in mixed transition years.
The Sun’s volatility is 0.3; The Tower’s is 1.0. The card part of each wick changes by 5 × (1.0 − 0.3) = 3.5 before rounding and 0–100 clipping. The candle body and the previous year’s opening can also change. Compare the unrounded wick extension separately from the final high and low if you want to understand the effect.
Computed comparison: Sun → Tower in card slot 1
Birth date: 1990-07-28. Card slots 2 and 3 remain The Star and Strength. First phase boundary: age 28. Every figure below is calculated from these inputs.
| Age | Sun baseline | Tower baseline | Aspects (both) | Sun close | Tower close | Change |
|---|---|---|---|---|---|---|
| 10 | 63.50 | 39.50 | 10.4 | 74 | 50 | -24 |
| 26 | 63.13 | 42.13 | 8.1 | 71 | 50 | -21 |
| 27 | 62.38 | 47.38 | 2.9 | 65 | 50 | -15 |
| 28 | 61.63 | 52.63 | 2.4 | 64 | 55 | -9 |
| 29 | 60.88 | 57.88 | -13.4 | 47 | 44 | -3 |
| 30 | 60.50 | 60.50 | -9.3 | 51 | 51 | 0 |
| 31 | 60.50 | 60.50 | 5.2 | 66 | 66 | 0 |
The aspect lists and sampled dates are identical in both runs. Closing scores match after the first-card blend ends; this does not establish predictive validity.
Why the change fades at the first Saturn return
The engine blends the old and new card baselines for four rows around a Saturn-return phase boundary. Changing the first card affects its share of that blend. Once the formative card is completely out of the baseline, closing scores match the original chart again. A candle’s opening still remembers the previous close, so check the year after a boundary before expecting the whole candle to match.
Changing the second card instead would affect the building years and both adjacent blends. Changing only the third card affects the harvest years and the second blend. This is a design choice that creates continuity; it is not a claim that a particular birthday produces a sudden psychological transformation.
A draw is a choice of symbolic inputs
“Draw 3 cards for me” selects three different cards in the browser. The numerical engine itself is deterministic once those cards and the birth date are fixed. Drawing again changes inputs, so a new chart is expected. Repeatedly drawing until a graph looks encouraging is a selection process, not evidence that the more pleasing graph is truer.
For a useful reflection exercise, save your original report, decide why you want to compare another card, and write down the expected numerical change before recalculating. Try Temperance, whose volatility is lower, if you want to investigate the difference between a calmer wick and a higher score. Calmness and a high baseline are separate parameters.
What the comparison establishes
This exercise establishes that the published rules account for the model’s output. It does not validate the tone values as objective facts about tarot, and it does not establish predictive accuracy. Another author could reasonably choose different weights and produce another chart from the same traditions.
Treat a dramatic-looking Tower chart as a way to ask about flexibility, contingencies or assumptions. It is not a warning that a disaster will happen. Keep health, money and safety decisions grounded in the circumstances you can verify.