All this talk of great acting performances in Kinda is meaningless unless I mention Simon Rouse's astonishing Hindle. Playing a deranged man well past the verge of a nervous breakdown while exhibiting rambunctious, childish behaviour could have been an invitation to seriously camp it up and overplay every single scene. However, Rouse's portrayal of Hindle is utterly, deadly serious, and the result is a truly frightening. Hindle is one of the most believable madmen ever seen in Doctor Who, and, as the closest thing to a humanoid villain in this story (Aris is nowhere near as threatening as the Mara that inhabits him), surely one of the more effective antagonists the series has ever produced.
By dispensing with Nyssa for the bulk of this story, one would think it would leave room for more scenes of The Doctor conversing with Tegan and Adric. But this isn't the case at all. Tegan, after transferring the Mara to Aris, falls asleep for most of this episode and the next; her part in the story is almost concluded by the half way point. Adric's role is as an informal mole to what the crazed Hindle and his new mental subordinate Sanders are up to, namely the destruction of the dome.
This leaves The Doctor companion-less, and so forms a tremendous bond with Todd in this episode as the scientist becomes the de facto companion for the rest of this story. Both The Doctor and Todd are present when the Box of Jhana is opened early in this episode. The effects of a similar experience with the Box have already driven Sanders mad, but Todd is unaffected by it. As Panna, the wise woman, later says, only women can handle the opening of the box without losing their minds. The Doctor only survived the experience because, in Panna's mind, he must be an idiot. We, of course, know that The Doctor is no idiot. He immediately understands that the Box of Jhana allows people to experience the world through the eyes of the Kinda. A regular male mind would try and decipher what the experience was about, resulting in madness. An idiot, on the other hand, would simply accept what was happening as he would anything else that he encounters in his day to day life.
Both a genius and an idiot accept that which they think is normal and devote no more thought to it than necessary. The similarities between the two are few, yet many. It's yet another fascinating concept that Kinda explores while managing to tell a cracking good story.