For instance, every time you take medicine you are trusting a pharmacist. You trust him because he claims to be a competent dispenser; because that claim has been verified by recognized medical authorities and a host of customers; and perhaps, because you have had other prescriptions made up by him before. Of course, it is not necessary to have all three elements present in any one act of trust. (a) We may, for example, have confidence in a man who has no confidence in himself; or, (b) we may trust him on the basis of our own experience without the confirming evidence of the experience of others; (c) and there is always a first time of trusting when we have no experience of our own to rely upon.

Teacher's Manual - Ten Basic Steps Toward Christian Maturity (p. 276)
Sixth Printing 1971 - Campus Crusade for Christ