Although summer does not arrive officially until the third week of June, the days preceding the solstice are filled with abundant light and increasing warmth. The Yellow Emperor's Classic of Medicine, which was compiled almost 300 years before the common era, describes the summer season and its energy in detail, with specific instructions as to how one may remain healthy through the season and into the autumn.
"In the months of Summer there is an abundance of sunshine and rain. The Heavenly energy descends, and the Earthly energy rises. When these energies merge, there is an intimate connection between Heaven and Earth. As a result, plants mature and animals, flowers and fruit appear abundantly..."
"One may retire somewhat later at this time of year, while still arising early. One should refrain from anger and stay physically active, to keep the skin breathing and to prevent the qi from stagnating. One can indulge a bit more than in other seasons, but should not overindulge..."
"Emotionally, it is important to be happy and easygoing and not hold grudges, so that the energy can flow freely and communicate between the external and the internal. In this way, illness may be averted... Problems in the Summer will cause injury to the Heart and will manifest in the Fall."
---The Yellow Emperor's Classic of Medicine
(circa 2nd century BCE)