Parallel structures can help you pair two ideas effectively. The more nearly parallel the two structures are, the stronger the connection between the ideas will be. Parallel structures are especially appropriate when two ideas are compared or contrasted.

History became popular, and historians became alarmed.

—WILL DURANT

I type in one place, but I write all over the house.

—TONI MORRISON

To create an especially forceful impression, writers may construct a balanced sentence, one with two clauses that mirror each other.

Mankind must put an end to war, or war will put an end to mankind.

—JOHN F. KENNEDY

With coordinating conjunctions

When you link ideas with a coordinating conjunction—and, but, or, nor, for, so, yet— try to make the ideas parallel in structure.

We performed whenever folks would listen and wherever they would pay.

With correlative conjunctions

Always use the same structure after both parts of any correlative conjunction—either . . . or, both . . . and, neither . . . nor, not . . . but, not only . . . but also, just as . . . so, whether . . . or.

The organization provided both scholarships for young artists and grants for established ones.

The edited sentence is more balanced. Both parts of the correlative conjunction (not only . . . but also) precede a verb.