Life can easily seen as a mistake, in which we are futile against its power. To be honest, it does truly feel like that sometimes. And in addition to neurological/chemical disturbances in cases of depression, one can truly adopt a certain pessimistic attitude towards life. At times, if we were to imagine a scenario where the individual were to control his brain's chemistry and for example serotonin levels. He will live a very joyful, happy life. Since, he eliminated any possibilities where the natural illnesses could penetrate and destroy his happiness. Once technology achieves this level of power, one will find it difficult to predicate the future of humanity as whole. It could either end up bad for all, or might have some salubirous consequences.

philosophy and science