It says that those who challenge to racism, colonialism, sexism, elitism, militarism, classism, exceptionalism, chauvinism, triumphalism, nationalism, religionism, .... are marginalized in historical accounts, yet their protests and "impossible" dreams are vital for change and justice.
About changing what is considered doable: ( A friend said that Bernie Sanders is bringing up the possibility of not being allied with the dictatorial Saudi regime, though it is a major weapons purchaser and ally. The friend said that this is an example of the "Overton Window".)
We can bring up the rights of nature, of trees, of rivers, of wetlands, of coral reefs, of animals, of wildlife, of wolves, of bears, of dolphins, of whales, of birds, of endangered species, of ecosystems, and of animals. We can also bring up the right to clean water and clean air. Here are links about the rights of nature. https://therightsofnature.org/articles ,