Topic sentences draw readers' attention to the main purpose of a piece of writing.
It sends the same message as a thesis or claim.

a woodchuck would chuck 12.5 wood : 3

theodore roosevelt 26th u.s. president : i admire his energy and passion. he was a fundamentally good man, brilliantly intelligent, possessed of extraordinary will and ability, supremely self-confident, bold, egalitarian, idealistic…. , lord, can we have him back?

fill in the blank

is slave

the scientific revolution brought us a renewed understanding of humanity and our place in the universe, new scientific equipment, and new laws as a basis for future scientific discovery.