The Time Traveller returns to the seat on the hill. He looks down on the Eloi, who don't realize that they are like cattle.
He gets sad about the passing of human intelligence, calling it suicide: people were smart enough to make the world a more comfortable place – but as the world got more comfortable, people became less smart.
He thinks that only a huge variety of needs and dangers keep people smart and strong. Without the dangers, the Eloi drifted toward "feeble prettiness" and the Morlocks drifted toward "mere mechanical industry" (10.4).
This would be a fine system if it were stable. But clearly the Morlocks ran out of food, and so they turned to the obvious replacement: the Eloi. This is the Time Traveller's final theory on this issue.
The Time Traveller takes another nap, then goes to open the Sphinx and get his Time Machine.
When he gets to the Sphinx, though, the doors are open.
The Time Traveller throws away his club. He suspects a trap, but he thinks he can deal with the Morlocks since he has matches.
But when the Morlocks try to trap him, he discovers that his matches will only light on the box, which was stolen in the last chapter.
Still, the Time Traveller manages to fight the Morlocks off while he reattaches the levers.