I would use this quote:
Power is in tearing human minds to pieces and putting them together again in new shapes of your own choosing.
This occurs in Book 3, chapter 3. Winston is listening to O'Brien preach about how the Party effectively gets what it wants. This completely embodies the text of 1984 because the book is about how a government goes about completely controlling its people. The warning of the book is to be on guard for a government that will surpass the boundaries of human rights and infringe upon things like choice, freedom, happiness, and ability. This quote also embodies the ideas of propaganda, manipulation, control and power. With this variety of themes, a student could argue many different particulars that this book explores.