What is meant by the phrase "1900 europeans believed the world was their oyster"

In the 1900"s the European nations were feeling pretty good about their situations. They had colonies around the globe, industrialization was good, their music and art were the envy of the world and they could have their pick of whatever they wanted. So, when they said "The world's my oyster" it meant that they could have whatever they wanted at the time.