These are quotes on Step 4 from various sources:
A business which takes no regular inventory usually goes broke. Taking commercial inventory is a fact-finding and a fact-facing process. It is an effort to discover the truth about the stock-in-trade. One object is to disclose damaged or unsalable goods, to get rid of them promptly and without regret. If the owner of the business is to be successful, he cannot fool himself about values.
We did exactly the same thing with our lives. We took stock honestly. First, we searched out the flaws in our make-up which caused our failure. Being convinced that self, manifested in various ways, was what had defeated us, we considered its common manifestations. -A.A. Big Book p.64