Medusans are a benevolent noncorporeal life form, but they normally prove lethal to any humanoids who see them. Although their thoughts are beautiful, their appearance is so hideous that it can drive humanoids insane.

Despite the risks involved in dealing with them, the Medusans have much to offer. On the cultural level, they can communicate their thoughts, which are described by Captain James Kirk as "the most sublime in the Galaxy", The Federation also has a deep interest in the Medusans interstellar navigation capabilities. Medusans can find their way across space time even from outside the boundaries of charted space to arrive precisely at their desired location.

Medusan navigation capabilities are not simply a skill which can be taught to humanoids. Their sense of place seems, from the human perspective, to be due as much to intuition as knowledge.

But exchange of information between Medusans and humans is extremely problermatic. It is difficult to describe, much less explain or understand, the Medusans lethal offensiveness, since few who have seen them have recovered from the effects. The sight of a Medusan almost instantaneously renders a person insane. The insanity usually takes the form of delusions, paranoia, and other symptoms of extreme affective disorder. The victim displays strong aggression, lashing out at anyone nearby, with brute strength engendered by the total madness into which he or she has plunged. Death follows rapidly, sometimes in the space of hours. Heart function, respiration, and brain activity cease without apparent cause.

Starfleet has developed a procedure for transporting Medusan ambassadors to and from their homeworld. Standard procedure requires a Medusan to be contained within a protective habitat; an average receptacle is a light-tight hexagonal container. The unit can be fitted with an antigravity generator so that it can be carried by two members. red protective visors, which cover the upper half of the face, must be worn by all personnel who may see the container to help protect them from the sight of a Medusan. Safety measures, such as clearing personnel form any corridors the Medusan is to pass through, are designed to minimize crew contact with the hazardous guest Teleportation leaves Medusans unsettled, despite their protective containers.

Vulcans are ideal for working closely with Medusans, but they still need the protection of the safety visors. Human telepaths, if properly trained in mental disciplines, are also well-suited to communing with them, but again the red safety visors are an absolute necessity. Dr Miranda Jones aid to Ambassador Kollos, is a human telepath who trained on Vulcan for four years before taking the assignment with the ambassador, Jones had the opportunity to turn a disability - blindness - into an invaluable asset. Incapable of seeing a Medusan, she is impervious to its repugancy.

The best way to communicate with a Medusan is through a mind-link. Again, Vulcans and trained telepaths are uniquely fitted to the task.

A mind-link between a Vulcan or a human telepath and a Medusan forms what can be called a corporate intelligence. The fusion creates a double entity that has the benefit of the knowledge and sensory capabilities of both, yet functions as one being. The potential for an exchange of knowledge between the Medusans and the Federation using this process is almost incalculable.

The Federation must proceed cautiously even with this promising technique. A mind-link has inherent dangers, the greatest of which is that the more successful the link, the greater the tendency of the participants to lose their separate identities. Even dissolving a mind-link has its hazards. The fused identity of Ambassador Kollos and the Vulcan Spock is nearly overwhelmed by the experience of the mind-link, when one of the safety precautions is neglected while dissolving the link, Spock is saved only by the prompt telepathic intervention of Dr Jones.

Medusans feel a profound sadness as what they perceive as our corporeal limitations and our inherent corporeal loneliness. Despite their effect on humanoids, they wish us no harm.