Damp, heat,cold , moisture

In the broadest application of the concept “yin” is all of the off switches or down regulators in the body and a large composite of the fluids in the body (both blood and body fluids (or jin and ye)).

Yin deficiency, then, is a weakness of these down regulation/cooling/calming functions. So hypertension for example, when the result of chronic stress (chronic yang excess) wears down this down regulation function (the “yin”) and then it allows the yang to rise resulting in hypertension. This is different when the yin is simply just not strong enough to balance a strong yang excess, say in liver fire - where the yin may be at an appropriately normal level.

In general terms why this distinction is important is that it is a somewhat western (maybe even human) inclination that when something is weak you strengthen it. But without understanding the yin and yang balance you can end up strengthening the fire (i.e. the imbalance) instead of resolving the condition as a whole.

One of the first lessons I learned in TCM was about the concept of yīn and yàng.

Qi isn’t just yàng . Nothing IS yàng or yīn! But Qi is yang compered to Xue.

For example: water is yàng compered to ice, But water is yīn compered to fire…

There is yīn and yàng in everything. But compered to xue (blood) qi is more yàng.

When you talk about kidney yīn defficiency, you must see yīn and yàng as in balance. In yīn deficiency there is less yīn, But the yàng levels are the Same as normal. So you see light yàng symptoms, because the body shows wat is most there. The solution is to put more yīn into It, so the levels of yīn and yàng are normal again. Of you should mistake the symptoms for an excess of yàng and sedate yàng, you’ll end up with a deficiency of both yīn and yàng.

Maciocia explains It very well in the foundations of Chinese medicine…but found a link with the same graphics…