But breathing through your mouth makes you a mouthbreather, no place you want to be. The sense of smell is very important, although probably mostly for little understood reasons, such as the aforementioned pheremonal data, but also for applications beyond sex - for example, schizophrenics may emit a certain odor that causes people to shun them, and in turn the social isolation makes them even crazier. *sniffs self* "Home made" magical incense serves as a good medium for meditation and the odors of herbs can trigger particularized emotions and thus help in one's journey to self-improvement. (Too much salvia smoking seems to screw with one's sense of smell, on an ancillary note.)