Brave New World is a controlled society that places restraints upon its citizens which results in the need for a depressant (soma) to ensure compliancy. The depressant grants relaxation and an escape from reality to anyone taking it. Soma is used as a replacement for LSD, Opium or Speed which are commonly used now. Huxley selected soma because it leaves the user with no thoughts, no understanding and no questioning. .
Soma puts the person into a void of all feeling. Soma is defined as "an intoxicating or hallucinogenic beverage, used as an offering to the Hindu gods and consumed by participants in Vedic ritual sacrifices." In the novel, Huxley contorts the word by the addition of no side effects after a dose. Much like common drugs now, the most opportune to take soma tablets is when the individual is conscious of being an individual. Huxley proves this when the Assistant Predestinator says "One cubic centimeter cures ten gloomy sentiments," (37 Huxley). The word soma evokes a feeling of domination throughout the novel because the government now controls the life of all citizens. Much like soma now, users take the drug and worship Ford even more. Huxley does not use the word in a religious connotation but in a controlling way.
In Brave New World, soma defines the way society is scrutinized daily. You can imagine that before it, civilization was filled with questions of how? who? and why?, which are now frowned upon. To the "perfect" society soma signifies an escape from the present and a means of understanding common occurrences. The entire foundation of Brave New World is built around the idea that the ideal conditions can be achieved by just "popping a pill". For anyone not taking the pill they are filled with images and thoughts which are condescending to the perfect circumstances. Soma presents the user a chance to slip away from what is happening and going off into a stupor state for a certain time frame.