As part of the Grimoiric Magical Tradition of the Middle
Ages, wisdom from more ancient cultures contributed to the development of a
complex magical theory. Alchemy, astrology, and mediumship all helped to shape
the traditions that made up a complex ceremonial magical system, parts of which have survived
to today. Within the realm of medieval astrology is a system of determining the most auspicious times for magical workings, which is still used by witches today.

In the expanse of the sky above us, float the stars and
planets. Their movement has influenced the magical schools that have developed
around the globe since humans had the capacity to look up. Planets got their
name from the fact that they were a special kind of star that wandered through
the fixed stars (

*planētai*means “wanderers”). There were 5 planets visible with the naked eye to the first civilizations.
Highly accomplished astronomers, the Babylonians had a
complex theology surrounding these planets, believing that the planets were
deities, each one governing the universe from a transparent sphere, called a
“heaven,” that revolved around the Earth. Each sphere was larger than the last
and enveloped the smaller spheres, much like layers of an onion, with the Earth
at the center.

Ptolemy organized the 5 planets, along with the Sun and the
Moon, based on their speed, so 7 heavens encased the Earth with the Moon being
the fastest and closest to Earth, then Mercury, Venus, the Sun, Mars, Jupiter
and finally Saturn, which was the slowest.

The sphere outside of Saturn was the heaven that held the
field of immovable stars, including the Zodiac. Outside of that were the divine
spheres. Before birth and after death, every soul had to come or go from Earth
by passing through the heavens. As we passed through these levels, our spirits
would pick up personal qualities - affected by being exposed to the powerful vibration of these
spheres.

This was the origin of what we now know as Astrology,
because it was postulated that the spheres would influence behavior. These
heavenly spheres were viewed as endowing their power, not just on the spirits of people, but
also on the moments of the day and on the days of the week. The priests of each
deity would calculate the most auspicious times in every day to work with their
patrons.

It’s a common practice today to reference a table of the rulers of the planetary hours before casting a spell. This gives us the chance to do our spell work during a time of day that vibrates with the most appropriate magical “frequency” for the intended purpose. There are many good online calculators that can provide you
with a very quick and accurate table of hourly rulers. But what if you can’t
use an online tool? What if you’re doing your spells in a cabin in the woods
with no internet access? Every witch should have the ability to
chart the rulers of the hours. Once you understand how these rulers came to be, you can create that chart easily from memory.

We have seven days of the week and each day belongs to one of the planetary rulers to be the primary ruler of the whole day. Sunday ("Sun-day") is the most obvious example and the primary ruler is the Sun. Monday and Saturday are ruled over by the Moon (“Moon-day”) and Saturn ("Saturn's-day"), respectively. The remaining days of the week are based on their association with Norse deities. Tuesday is ruled by Týr ("Týr's-day"), Norse god of law and heroism, who corresponds to the Roman god, Mars. Wednesday is ruled by Woden ("Woden's-day") who corresponds to the Roman god Mercury; both are gods of travelers, magic and learning. Thursday is ruled by the Norse god of thunder ("Thor's-day") and corresponds to the Roman god, Jupiter. Venus, goddess of love, who is seen in the Norse pantheon as Freya ("Freya's-day") rules Friday.

A ruler of a day governs the first hour, which begins at dawn. The rulers of each of the subsequent hours are laid out in a specific order that forever repeats throughout the 24 hours of each of the seven days of the week. Let’s start with an example day – Monday – which is ruled by the Moon. This means that the Moon will always be the ruler of the first hour on Mondays. Each daily period following the Moon’s governance will be ruled by one of the remaining six planets, but always in the same sequence. To find this sequence, write out a repeating sequence of the planets in order from slowest to fastest. We know the Moon is ruler of the first hour on Mondays and it is the fastest planet, so it is the last planet in the speed sequence; we must return to the slowest planet and begin the sequence again. The second hour will be Saturn, the third will be Jupiter, then Mars, the Sun, Venus, Mercury and lastly, the Moon again. Continue to repeat that sequence until there are 24 rulers on your list. You have listed the sequence of the rulers of all the hours from sunrise on any Monday, through the night time, to sunrise on the following Tuesday morning.

If you continued the sequence into Tuesday and the remaining hours of the week, you would create a chart like the one below. Notice how the sequence for all the hours of the week flows from day into night, then into the next day, then continues without change through all the hours of each day and night for the rest of the week. The sequence determines which day of the week has arrived because of the particular ruler of the first hour. Hour 1 of the daytime always begins with sunrise. Hour 1 of the night time (or hour 13 in some tables) always begins with sunset.

In the contemporary age, the period of the day that we call
an “hour” is a specific length – always 60 minutes, each made up of 60 seconds.
But the hours ruled over by each of the planetary rulers are not always 60
minutes long. This is because the Babylonians reckoned their hour as
one-twelfth of the daylight time or the night time. That is, both the day time
and the night time, separately, were divided into twelve equal periods based on
sunrise and sunset. Except on the equinoxes, the amount of daylight we
experience between sunrise and sunset is more than 12 hours in spring and
summer and less than 12 hours in autumn and winter. So if we are in spring or
summer, when the day time totals more than 12 hours, each one-twelfth period of
that time is going to last greater than 60 minutes. In autumn or winter, each
one-twelfth period will be less than 60 minutes.

To determine the length of each period, you will first need
to know the moment of sunrise and sunset. The moment of sunrise and sunset are
actually calculated by astronomers based on your location on the globe and the
date of interest. They will be different for each latitude because of the
curvature of the Earth, the tilt of its axis and the date. These times are
commonly published in local newspapers and almanacs, as well as pagan calendars,
but are also readily available online through reliable sites like NOAA. For the
sake of this exercise, let’s assume that we looked in our almanac to find that our
sunrise time will be 6:42 AM, our sunset time will be 7:32 PM and we decided
that the best period for our spell will be the hour of Mars.

First, it is helpful to convert sunset into the 24-hour
clock. Simply add 12 to any time between 1:00 PM and 11:59 PM. For example, a
sunset of 7:32 PM will become 19:32.

I find this whole process is made easier by converting clock
times into decimal hours, because it allows us to use standard math until the very
end. Simple arithmetic of decimals works easily on a calculator, while
arithmetic of clock time does not. You can convert clock times into decimal
hours by dividing just the minutes by 60. So our sunrise time of 6:42 AM will
become 6.78 (42 ÷ 60 = 0.78). Our sunset time of 19:32 will become 19.53 (32 ÷ 60
= 0.53).

Next, subtract the smaller from the larger: 19.53 – 6.78 = 12.75
hours. This result is the amount total of daylight time that will shine on our
Monday; there are 12.75 hours of daylight between sunrise and sunset.

Divide this total time by 12. For example: 12.75 hours ÷ 12
periods = 1.06 hours/period. This means that every period ruled by each planet,
beginning with the Moon, will be 1.06 hours long. We call these periods
“hours,” but it’s clear from their length that they are not clock-hours as we know
them.

Remember that our hour of interest is ruled by Mars. If we refer
to our list of the rulers of Monday, we find that Mars is the 4

^{th}period.
Multiply the length of the periods, which we found to be
1.06 hours/period, by the number of the period for Mars on our day, which is 4.
This gives us a result of 4.24 (1.06 hours/period x 4 periods = 4.24 hours).
The Mars period will end when the next period begins, so we can multiply by 5
to find the end time: 5.30 (1.06 hours/period x 5 periods = 5.30 hours).

Now add both of these values to the decimal sunrise time:

Now add both of these values to the decimal sunrise time:

Period of Mars, starts: 6.78 (sunrise) + 4.24
hours = 11.02

Period of Mars, ends: 6.78 (sunrise) + 5.30 hours = 12.08

Finally, convert both of the times back to clock time by
multiplying just the minutes by 60:

Period of Mars, starts: 11.02 becomes 11:01 AM
(.02 x 60 = 1.2 minutes, rounded to 1).

Period of Mars, ends: 12.08 becomes 12:05 PM (.08 x 60 = 4.8
minutes, rounded to 5).

If necessary, you can convert any result that is 24-hour
time back to 12-hour by subtracting 12.

As witches, we do most of our spells after sunset, when the
darkness provides us with protection and secrecy and helps to generate the appropriate head-space. Finding
the correct period after dark often produces more difficulty because of the
transition from PM to AM at midnight. However, a simple reversal can resolve
all difficulty, though the process seems unconventional. I find that the best
way to handle the difficulty is to treat the night as if it was the day, then
work all the steps normally.

Your periods will start with sunset and will end with the
sunrise on the following date. Convert the AM times to 24-hour time, instead of
the PM times. Complete all calculations the same. At the very end, convert any
time between 13:00 and 23:59 back to 12-hour time as AM, instead of as PM.

I recommend keeping all values rounded to two decimal places
until the very end. This minimizes any distortion of the period start times. I
also find it helpful to ensure that my spell work happens at least 5 minutes
past the chosen period start time, just to be sure I’m well past any minutes
affected by rounding, putting me solidly into the correct period before I
begin.

Whenever possible, I advocate using a reliable planetary
rulers calculator, but if you can’t get to one, you should have this
technique tucked in your book of shadows as a back-up plan.