Why does Douglass feel reluctant to speak at the anti-slavery convention in Nantucket?

Frederick Douglass felt reluctant to speak at the anti-slavery convention at Nantucket because at that time he felt like a  slave as yet.

Explanation:

Frederick Douglass, when sharing his experience as a slave at an anti-slavery meeting at New Bedford, was overheard by a banker. Impressed by his wisdom and articulation of words, he invited Douglass to address an Anti-Slavery Convention at Nantucket.

This was to be attended by various white activists as well. This made Douglass nervous and reluctant as he had never addressed a big crowd before and he at that time was yet felt like a slave, not having overcome the inhibitions as yet.

He, however, went ahead and addressed the crowd and gave a speech on his views and experience as a slave.

1.the hosts on two opposing mountains stood,  

2.thick as the foliage of the waving wood;  

3.between them an extensive valley lay,  

4.o'er which the gleaming armour pour'd the day,  

5.when from the camp of the philistine foes,

6. dreadful to view, a mighty warrior rose; in the dire deeds of bleeding battle skill'd,