I've never understood what people didn't see in this episode. All the time, I hear people complain that the four-parter 'An Unearthly Child' is one great hook and three episodes of people faffing about in animal furs, and every time I watch this one, I wonder if they haven't suffered some sort of head trauma that leaves them unable to appreciate awesomeness.
Because this is great stuff. Really, crackingly great stuff. Hartnell's wonderful line, "If you could touch the alien sand and hear the cries of strange birds, and watch them wheel in another sky, would that satisfy you?" Russell's iconic statement, "His name's not Foreman. Who is he? Doctor who?" Derek Newark's magnificent, anguished cries as he tries to make fire spring forth from the sticks, and the brilliantly poetic taunts of his people as he fails. "Tomorrow, I will kill many bears for you. Many warm skins." "I think that tomorrow you will stand here and rub your hands together, and ask Orb to bring you fire...and the bears will stay warm in their own skins."
And the climax of the episode. Za and Kal exhorting the crowd brilliantly, finding the basic levers of their tribe's primal fears and hopes and pulling on them with all their force. "Za will leave you to the tiger!" Kal cries, certain he has the whip hand. "Za will leave you to the cold!" And then, when the tables turn, Za twists Kal's rhetoric right back against him. These aren't stupid people. Primitive, unlearned, but by no means dumb.
And scary, too. There's a raw edge to these episodes I don't think Doctor Who will ever regain. The Doctor, Ian, Susan and Barbara are among people that have absolutely no qualms about casual, brutal violence, and everyone involved knows it. Every moment, it feels like one of the tribe could just decide to smash a rock through someone's skull and end the series for good after only two episodes. That tension is greatly evoked through the acting and the direction; the cliffhanger, where Ian notices all the holes in the titular Cave's deceased inhabitants, feels almost redundant. This is Doctor Who at its most nerve-racking, no matter what the Hinchcliffe fans might tell you. "The Cave of Skulls" might not have the same virtues that "An Unearthly Child" had, but I frankly think I like it even more.