The third principle is the acceptance and encouragement to spiritual growth of one another.
The fourth principle is the free and responsible search for truth and meaning.
It seems apparent that the engagement with the third principle requires some success with the fourth. A person can't give what the person doesn't have. Encouragement presumes that the person doing the encouraging has some experience with what they are encouraging.
In the Unitarian Universalist church there are plenty of caterpillars. Are there any butterflies? If there are butterflies among us are they encouraging us caterpillars to be patient and continue to eat and digest our leaves because butterflydoom is going to come if we are patient and persistent.
Is the caterpillar aware that it is going to become a butterfly? Are you aware that you can become a buddha?
Some people have this awareness that within them is a piece of the Divine. Others have no idea. Nobody has ever told them to look within. If the person did look within and was confused, perplexed, bored, frightened, they stopped. They didn't stick with it. To pursue the truth of the Divine within takes courage, persistence, and faith.
It helps to have someone further along the path of the spirit to encourage others to come along. Most people will not listen because they don't believe the encourager has anything of value to impart. Jesus says in Matthew 13:4-9: