Aime Cesarie speaks beautifully in this passage, writing deeply on how he will fight for his people, even if that is all he can do. He says "If all I can do is speak, it is for you I shall speak." This shows his devotion to his cause, how he will be an ambassador for his people, thos who are afraid or to weak to stand up for what they believe is right. He sees pain and calamities within his native land and he is finally speaking up.
The line that I beleive is the most forceful line in his statement, the one that is practically his mission statement is "My mouth shall be the mouth of those calamities that have no mouth, my voice the freedom of those who break down in the solitary confinement of dispair." This is a powerful line that he is there for his people, that he will not let them down, and that they will be free from opression and dispair.