Which organ is considered the root of post-natal life?

The spleen is recognized as the root of post-natal life because it plays a crucial role in the digestion and transformation of food into Qi (vital energy), blood, and bodily fluids, which are essential for sustaining life after birth. In Traditional Chinese Medicine (TCM), the spleen is vital for the process of extracting nourishment from food, which directly supports the body's energy levels and overall health. This function is especially important in the development and maintenance of post-natal vitality, as it reflects how effectively the body can utilize the nutrition gained from the environment.

Additionally, the spleen is involved in the production of blood and the management of fluids in the body, which further reinforces its significance in post-natal life. It also contributes to strengthening the body’s defenses, helping to foster a healthy immune response. Hence, the spleen's multifaceted roles ensure that it is viewed as foundational to life after birth, underscoring its classification as the root of post-natal existence in TCM theory.