This sentence is in the passive voice. Passive voice is when the object of the action becomes the subject, or in other words, the verb is being done to the subject.
In most English sentences with an action verb, the subject carries out the action denoted by the verb. Since the subject acts upon the verb, the sentences are said to be active. However, you can change the order of words for the subject to be no longer active but being acted upon by the verb. In that case, the sentence becomes a passive voice sentence.
The sentence above is in the passive voice. You can see that the active sentence's direct object has been moved into the subject slot (the cascading waterfall), the active's sentence subject has been suppressed, and a form of auxiliary <em>verb</em> has been added to the main verb (was).
<span>Postwar science fiction authors wrote to warn society of the potential results of its values, while beat generation authors wrote to reject society’s values. </span>
