Final answer:
The nurse's guiding principle throughout the process of obtaining a history from a client who has pain should be that pain is whatever the client says it is. Pain is a subjective experience that cannot be objectively measured or confirmed. Objective data should complement the client's subjective report, not override it.
Step-by-step explanation:
The nurse's guiding principle throughout the process of obtaining a history from a client who has pain should be that pain is whatever the client says it is.
Pain is a subjective experience, meaning it cannot be objectively measured or confirmed by clinical tests. Therefore, the nurse should prioritize and trust the client's self-report of pain intensity and quality.
Objective data, such as vital signs and physical examination findings, are important to consider in assessing pain, but they should be used to complement the client's subjective report and not override it.