"What does it mean to have seen Truth's gate?"

"If you attempt transmutation that requires energy or matter you don't have, your consciousness is taken to the metaphysical realm. There, Truth gives your soul material from beyond the gate in exchange for a part of your body. Some material can only be gotten from beyond the gate -- soulstuff from people who've died, for example."

"I see. None of this sounds to me like reasons to suspect myself doomed to failure. If you teach me alchemy, I will kill Homunculus for you."

"Thank you."

"A threat to the world is, at present, a threat to me. I would be a fool to ignore it."

"... and rightly. I'll start by teaching you the chi technique, which will help you identify his subordinates."

"I am ready to learn."

He starts with meditation exercises! ... tedious, mind-numbing meditation exercises.

She knows how to meditate, she can pick it up quickly.

It's slightly harder while walking, but he's still impressed. He looks for the right signs in her chi so he can let her know whether she's on the right track with any particular mental trick.

A lifetime of channeling the Force and studying its techniques have given her a great many tricks to try.

Eventually they can see the wagon on the horizon.

Does it seem likely to be dangerous?

At least one person appears to be heavily armed.

Primitive weapons. Not much of a threat.

No, probably not. 

They get closer.

"Hello!" Hohenheim says in Xingese. "Are you headed to Kashgar?"

Armed guy comes forward. "Yes."

"Oh good," he says, smiling, before collapsing into the sand.

She reaches out with the Force, assessing his condition.

... he really hasn't eaten in a while. About a week, from his condition. He could probably fix it with the power he has but he's choosing not to.

Tsk. Foolish old man.

She crouches down over him and holds a hand above his chest, feeding power into him like vivifying ice burning through his veins.

He gurgles a bit, then stands up. He shudders. "That wasn't necessary. I've gone for longer without food."

The armed man stares. "... are you alchemists?" He says in his language.

"Of sorts," Hohenheim replies, shooting a glance at Ellie. "We can heal people or animals if you have any injured or sick."