Comstock Act, federal statute passed by the U.S. Congress in 1873. Named for Anthony Comstock, a zealous crusader against what he considered to be obscenity, the act criminalized publication, distribution, and possession of information about or devices or medications for ‘unlawful’ abortion or contraception.
The poet compared imagination to a soaring bird because imagination is limitless, it can do anything and go anywhere, much like a soaring bird, who has the freedom and capabilites to do anything. Both are completely free of bounds.