I'd avoid putting anything in parentheses. If the idea doesn't fit into the text, then just omit it. If you don't want to omit it, then find a way to make it fit.
Robinson’s education of Friday recalls the processes of modern colonialism, which follows a recurrent pattern: First, he manages to exploit and dominate nature, as well as shape his own destiny through his work and the interpretation of his achievements in the light of the Bible. He is convinced he has God on his side. Second, he gives Friday a new name which is meant always to remind the Indian of his debt to the white man for saving him on a Friday; Friday, on the other hand, must call Crusoe master. Third, Robinson clothed Friday by giving him worn-out European clothes; Friday “was very pleased to see himself almost as well dressed as his master.” Fourth, Robinson does not bother to learn Friday’s language, but teaches him enough English to understand him and follow his orders. He also teaches Friday the principles of Christianity. Last, Robinson never gives Friday a weapon and is even careful never to let him see how he loads his gun. In short, Robinson has three great advantages over Friday: a technical advantage in his superior weapons and utensils; a linguistic advantage, speaking only in English; and a spiritual and religious advantage in Christianity. The island turns out to be the ideal place for Robinson to prove himself as a colonizer and a hero.