An audit intern from a local state university is assisting with the audit of a major attestation client. The audit intern has been tasked with auditing the client's purchases$-$payables cycle. As this is the audit intern's first ever audit, the intern approaches you, their supervisor $,$ to help gain an understanding and general overview of the process. Which of the following statements would be the most helpful for the audit intern in understanding the overaching goal of auditing the purchases$-$payables cycle?