Ye know how - To show them the folly of their embracing the new views which they had adopted, he reminds them of past times, and particularly of the strength of the attachment which they had evinced for him in former days.
Through infirmity of the flesh - Greek “Weakness” (ἀσθένειαν astheneian); compare the 1 Corinthians 2:3 note; 2 Corinthians 10:10; 2 Corinthians 12:7 notes.