Note 2 at 2 Cor. 10:13: This word "measure" is used five times in verses 13-15. However, there were two Greek words translated by this one English word. The first (v. 13) and the fifth (v. 15) time this word "measure" was translated from the Greek word "ametros," which means "without measure; immense." Paul is using this word in the sense of saying, "we will not boast of things which are impossible to measure." The other three times, the Greek word "metron" was used, which meant "an instrument for measuring; a rule or standard of judgment."

So, Paul is continuing his argument against those he mentioned in verse 12 who made great claims, but had no track record by which to evaluate them (see note 1 at v. 12). He is not making claims about his authority which can not be measured or proven. But God had wrought many miracles through him, which gave them a standard with which to judge him. They had seen him in action, "a measure to reach even unto you."

In verse 14, Paul is saying, "We are not claiming something which you have not witnessed first hand. We are the ones who came and brought the gospel unto you." Then in verse 15, he again reminds them that these facts make his right to apostleship more than unmeasurable claims. He is not talking about what someone else has done. He is speaking of his own actions, which the Corinthians were well aware of.