Most Yang: A san fu Explainer
The Traditional Chinese calendar is split into 24 solar terms. These are delineations within the four broader seasons of Spring, Summer, Autumn, and Winter. The 24 solar terms map onto periods of the year which are relatively more yin or more yang. During the summer and start of autumn there are three periods of time which are called the San Fu. These San Fu, the 'dog days' of summer, are the most yang times of the entire year.
There are basically endless attributions for both yin and yang. Yin qualities are darker, cooler, wetter. Yang is about hotter, brighter, and drier. Yin is more slow-moving, yang is quicker. Yin and yang do not exist alone. They always exist relative to one another. There is no yin without yang, and vice versa. If you're familiar with the yin-yang symbol, you will recall there is a drop of yin in the yang, and a drop of yang in the yin.
San Fu days are not just hotter, though they sometimes do contain very hot days. These are times of year when the most yang animals may be present, the most yang situations can arise, and the most yang outcomes are likely to occur. Tracking the more relative yin and yang as it shows up on the calendar also has medical importance. Certain times of year are especially good for certain treatments. During the San Fu we can make use of the free-floating atmospheric yang to support our body system's yang.
Chinese medicine is not just a medicine of the body. Instead, it tends to the entire system: from the most yang (fleeting mental image) to the most yin (death), and everything in between. It is as much a medicine of the physical as it is of energetics.
In Chinese medicine, yang is associated with the Wei qi, called the defensive qi. This is our body's first line of defense. You can think of this as a three part system: the 'personal bubble' a few inches off of our skin, any body hair, and then the skin itself. When you have a strong wei qi you can adequately regulate your temperature in all aspects. Not just body temperature, but social temperature and energetic temperature. Strong wei qi can also manifest as supple skin and a strong immune system.
There's a medical maxim which is apt here, "Heaven initiates and Earth responds". The concept holds that things get generated in the 'heavenly' (most yang) realm before they show up on earth. This can be heaven as we imagine it, but it also means the sky, our minds, and the most yang of any given situation. Put simply, the clouds make rain before the rain touches earth. The few inches just above our skin is the most yang part of this wei qi system.
A practice which can strengthen the defensive qi is moxibustion. One common form of moxibustion involves burning a mugwort stick in proximity to skin so that it warms an acupuncture point. Another form involves lighting a tiny cone of moxibustion on fire while it is touching the skin. While there are many types of moxibustion techniques, these two specific techniques are what I use during San Fu treatments. This treatment tonifies - builds up - the wei qi at the heavenly levels, and that will benefit the earthly levels of immunity
Moxibustion treatment during San Fu days offer a unique opportunity to stimulate the body's wei qi. It is commonly held that a full course of San Fu treatment will give you enough oomph for an entire year of immune benefit.
