Don’t use “this” or “that” as a subject.

This, that or these should be used only as an adjective and not as a subject. Say I love these books, rather than These are the books I love. Instead of using this or that as the subject of your sentence, spell out what this or that refers to. For example, don’t begin a sentence with This means that . . . . Instead, say The defendant’s refusal to honor the contract means that . . . . Using this or that as a subject requires your readers to look back to the previous sentence to determine what this or that refers to and defeats the goal of keeping the readers’ eyes moving.

But you may use this or that as an adjective. Indeed, using phrases such as this theory or that contract to refer to material in the preceding sentence is a helpful transition technique. Thus, the theory of the corporate veil in one sentence can become that theory in the next sentence.