Originally Salvia only grew in the Sierra Madre Mountains in Oaxaca, Mexico, where Mazatec shamans used this plant in their sacred rituals. To enter the visionary state of consciousness they collected the leaves of this plant and chewed on them for about 30 minutes. This is practiced even today, both in Mexico and all around the world.
Salvia divinorum is known by most people as a smokable herb, but this is actually a practice that is fairly recent. The difference with chewing is that the effect comes on immediately, within half a minute or so, is much more intense and lasts much shorter, namely 10 minutes instead of one or two hours.
Salvia extract is known to generate a very rich and overwhelming hallucinatory state that could provide a 'dark' as well as illuminating learning experience. Even with the traditional usage of chewing the leaves it is common practice to have one or two sober sitters taking care of the one having the experience.
It is very easy to grow your own Salvia. Moreover, once it's of a certain size you can take cuttings from it and multiply the number of plants you have again and again.