What Ayurvedic texts describe shadows as sweet or cold?

Question

As I discuss in this question, by far the most popular school of Hindu philosophy is the Vedanta school. But there are five other Astika or orthodox schools of Hindu philosophy: Purva Mimamsa, Samkhya, Yoga, Vaisheshika, and Nyaya.  My question is about the Yoga school, which believed in Purushas or souls, Prakriti of matter/energy, and Ishwara or God. And it’s defining text is Patanjali’s Yoga Sutras.

Now the Yoga Bhashya Vivarana is a subcommentary by the Advaita philosopher Adi Shankaracharya on Vyasa’s Yoga Bhashya, which is itself a commentary on Patanjali’s Yoga Sutras. In this section of the Yoga Bhashya Vivarana, Adi Shankaracharya defends the fact that Ishwara can perceive the world without the use of sense organs. He says that makes sense, given that even humans can perceive darkness without the use of the eye. But then the Purvapakshi or hypothetical opponent raises the objection that darkness isn’t actually a real thing, just the absence of light. Here is how Adi Shankaracharya responds to that:

Again, if darkness were merely an absence, then it should not appear as a weak darkness in brilliant moonlight at night; it ought to be destroyed by that all-pervading light in whose brightness it stands. With an actual thing in the brightness, it is natural that it should have distinctions of weakness and intensity and so on, but not with an absence, for that can have no such distinctions.... Again, in the medical texts, the shadow (of the patient) is said to be sweet, or to be cold. But there can be no sweetness or coldness of what is not a thing. And they call darkness good or bad for certain eye conditions: but an absence could not be so characterized. Furthermore, a shadow is perceived as from a light. If darkness were a non-existent, how could there be – within the circle of illumination – a shadow caused by the light?

I’m interested in the part in bold. My question is, which Ayurvedic texts describe a person’s shadow as sweet or cold?

It’s interesting to note, by the way, that Adi Shankaracharya is citing Ayurvedic texts as an authority. That’s because Ayurveda is one of the four Upavedas.

Answer 1

This has been covered in Caraka Samhita's Pannarupiyam Indriyam Adhyaya i.e. Indriya Sthana Chapter 7.Fatal signs of changes in shadows, complexion, and luster.

In the section under features of fatal prognosis as per shadows following is stated

If any sorts of deformity observed in body parts in the shadow of the person in moonlight, sunlight, light of a lamp, water or mirror. He should be considered as dead.

Observation of shadow of a patient as broken, torn, hazy, devoid of certain organs, seeing excess organs, not conspicuous, bifurcated, deformed and without head, such other similar abnormal shadows if develops without any apparent cause it is considered as severe morbidity.[5-6]

Distortion of shadow in respect of changes in shape, measurement, colour and lustre should be considered as ominous sign even in healthy individual.[7]

Seems that the physician is able to determine the lifespan remaining in the patient by examining shadow of the patient

Now Ayurveda states all living and non-living things are made up of 5 fundamental elements or Pancha Mahabhuta - Akasa, Vayu, Agni, Jala and Prithvi. In case of shadows they would be characterized as follows

And their role in complexion and lustre under applied inferences (vidhi vimarsha) is given as follows

Qualities of Pancha-mahabhuta are:

Akasha- sound, auditory organ, all orifices and distinctness.

Vayu – touch tactile organ, all activities, movements in all body parts and lightness.

Tejas– vision, visual organ, complexion, heat, splendor, digestion, intolerance, sharpness and valor.

Apa- taste, gustatory organ, all liquidity, heaviness, coldness, unctuousness and semen and

Parthiva (i.e., those that have qualities of the prithvi element) - smell, olfactory organ, hardness and heaviness.(Su.Sha.1/19)

From above it seems that "cold" and "sweet" would come under Apa mahabhuta as degrees of taste and coldness falls under it.