I used the term physical as a quote from the author, who also used in quotes (hence the python style quotes in my post). But "physical" somewhat captures the m

I used the term physical as a quote from the author, who also used in quotes (hence the python style quotes in my post). But "physical" somewhat captures the medical view on depression, as something distinct from the ordinary spectrum of "healthy" emotions, and with causes that are primarily internal not external (although, as you say, all thoughts and emotions are ultimately mediated through physical processes in the brain). So my point wasn't that sadness is non-physical, but rather all experiences are physical, and most experiences belong to the spectrum of human emotions, which are influenced by external and social events, thought not always in the most obvious way (hence my opposition to the "just get over it" strawman, since "just get over it" might be a bad response to mere sadness too). I also don't have a strong opinion on chemical intervention, except that I would hold them to a higher standard of evidence since I have a stronger prior on the root cause being social and emotional, rather than a congenital inbalance in brain chemistry. It's plausible that they work, and if they work, they should be used.