The first thing I do when I start a new writing project is to search the works of other writers already published on the subject.
Every good writer does the same thing.
Simply ripping off the work product of another artist is illegal. As time and technologies progressed, copyright laws progressively tightened in response. Each new technological leap presented those with vested interests in intellectual properties with a fresh challenge to what they saw as their rights. By the dawn of the 20th century it became less about the rights of starving artists and much more about the rights of large publishing concerns. In the US, copyright periods were steadily lengthened from their original 14 years.