Sentence:  What mortal, when he saw, / Life's voyage done, his heavenly Friend, / Could ever yet dare tell him fearlessly: / 'I have kept uninfring'd my nature's law; / The <WSD>inly</WSD>-written chart thou gavest me / To guide me, I have steer'd by to the end'? 
Meaning of the word marked with <WSD> tags:  Inwardly, within; internally; secretly.