Cannabis really is an amazing plant. Indeed, cannabis has been cultivated for its healing properties from as far back as 2737 BCE. You might say it has evolved WITH humans, much like the modern dairy cow, domesticated dog, or chicken. Cannabis has been praised in ancient Ayurvedic healing, regarded as the ‘single most important’ herb by traditional Chinese medicine and used by Coptic Christians in the early millennium. As Michael Pollan says:

"Never has a naturally occurring herb been more important to modern medicine".

It’s safety and efficacy can’t be denied. In fact, based on anthropological records, you could say that it has had more human testing than any other pharmaceutical in the history of mankind (even pre-dating distillation).

There is still plenty to understand about this bit of botany, and it is an exciting time to now be able to apply the latest medical technology and research to the subject. Many large steps have been made, but this is an evolving study. Pharmaceutical companies have attempted (and failed) to patent and isolate single components in order to more easily market the drug—ignoring the harmonious "ensemble" effect of the plant as a whole. Frankly, we don’t yet have a grasp on the why, we just know the how. Below are the widely accepted and researched ailments that have been widely treated using cannabis:

Pain, depression, fatigue, stress, lack of appetite, headaches, insomnia, nausea, muscle spasms, inflammation, cancer, anxiety, appetite suppression, autoimmune deficiencies, tumors, seizures, and many others are being realized the more we research.

Sources: Center for Medical Cannabis Research, University of California