Sadness roots inside like the seed of depression, just waiting for the right conditions to spread and encroaches every last one of the vessels with its dark, hopeless roots. Sadness is what the heart feels like when being cut through by a knife from a best friend; it is the suffocating feeling drowning in the deepest place of the ocean—helplessly looking at everything around; it is the feeling when the body lost its center of gravity that you cannot grasp anything and kept falling down. Sadness reaches each one of us inevitably without a doorbell, but we can welcome him as a long-time-no-see friend. After all, the things that make us sad are exactly what we care about and need to deal with. Acknowledging sadness is not cowardness, it's actually a manifestation of the courage of letting go of the past and moving on with hope and dream.
Yes, again, the bottom semicircle represents the human brain, the theme of this illustration is "numbness”. The raindrops falling from clouds imply the tear, and each element(glass bottles) represents a sense of suffocation and an inability to escape from the cage of sadness.