In her 1962 book, Silent Spring, Rachel Carson was trying to alert the public to the dangers of pesticides. She was trying to make people more environmentally aware.
At the time that Carson wrote the book, there was very little environmental consciousness in the United States. People were not really aware of the possibility that chemicals and things like that could actually harm the environment. Chemicals were identified with progress. DDT was an example of that. It had been something of a wonder pesticide and was very popular.
What Carson was doing was trying to change this view. She was trying to get people to realize that pesticides were capable of causing harm and that they had actually been causing great harm to bird populations especially.