Smith had relapsed into his attitude of passive waiting.  Not understanding what it was all about, he had done only the minimum he had to do.  But guns he had seen before, in the hands of men on Mars, and the expression on Jill's face at having one aimed at her he did not like.  He grokked that this was one of the critical cusps in the growth of a being wherein contemplation must bring forth right action in order to permit further growth.  He acted.