Notes on Healing
There are three types of healing: clerical, magical (which includes alchemical potions) and medical.
Clerical healing is miraculous in nature, but is usually quite subtle, and easily interpreted as luck or coincidence. The typical scenario is for the cleric to invoke the aid of an appropriate saint while the patient is being examined, and if successful, it turns out the wounds are not as serious as they looked (or even as the patient believed). In terms of game mechanics, this is true healing, and if done before the patient is examined, it can even bring a character below the death threshold "back to life" - because the injury was not there to begin with. In some cases, such as The Great Cure, the results are much more spectacular, a literal "laying on of hands" with visibly miraculous healing.
Magical healing is, effectively, crazy gluing the wound shut so perfectly that it is like it's not there at all. It won't bring an ostensibly dead character back to life, but in all other ways, the wound is healed. The drawback is that, until the wound has healed naturally, the magic can be dispelled and the wound would return. Dispelling enough wounds at once could easily kill the character. This includes alchemical healing potions.
Medical healing does not have an immediate effect. Rather, it enhances the natural healing rate. Body recovery is increased by the square root (round down) of the physician's experience level, starting from whatever natural healing rate is indicated by the character's level of activity. Those under the care of a high level physician can heal quickly, even while engaging in strenuous activity like combat.
Note 1: At level 10, a physician can create healing cordial that are the equivalent of a cleric's "Cure Minor Wounds," with a 75% chance of restoring 6-10 points of Body. Unlike alchemical potions, this is not magical, it is true healing. These potions require seven magical materials, four of which must be liquids, none of which are inexpensive or common, and require 1-4 weeks to prepare, minus one day per experience level. 5-10 doses result.
Note 2: At level 15, a physician can create a cordial which will cure any disease (the equivalent of the clerical "Cure Disease" invocation) with a 75% chance of success. This requires 21 magical materials (seven of which must be liquids) of "rarity and great cost," 1-4 weeks to prepare, and produces 5-10 doses.
Note 3: At level 19, a physical can prepare a cordial that is equivalent of a cleric's "Cure Serious Wounds," again with a 75% chance of success, restoring 6-20 points of Body. The process to prepare is the same as for the cure disease cordial.