Does the agent's prior knowledge affect the validity of the agency if established by two witnesses?

Primary text

If two witnesses testify that an absent principal appointed an agent who is present, and the agent states, 'I was not aware of this, but I am acting on his behalf,' the agency is established. This is because the statement implies, 'I became aware now,' and the acceptance of agency can occur later. The presence or knowledge of the agent is not a precondition for the validity of the mandate, so the agent's previous ignorance does not invalidate it.