求大神指教如何准确分清第一段的结构

Ly2016

阅读做的怀疑人生了，每每读完第一段脑子里一团浆糊，作者到底想说啥？-如何分清作者的总论点和引文？？，求大神指教~，再弱弱的补充一个问题，如何准确的总结出文章的话题？？，话题和总论点之间的关系是什么呢？？
贴一篇第一段做例子吧

The settlement of the United States has occupied (occupy: to engage the attention or energies of) traditional historians since 1893 when Frederick Jackson Turner developed his Frontier Thesis, a thesis that explained American development in terms of westward expansion. From the perspective of women’s history, Turner’s exclusively masculine assumptions constitute a major drawback: his defenders and critics alike have reconstructed men’s, not women’s, lives on the frontier. However, precisely because of this masculine orientation, revising the Frontier Thesis by focusing on women’s experience introduces new themes into women’s history—woman as lawmaker and entrepreneur—and, consequently, new interpretations of women’s relationship to capital, labor, and statute.