The terms active and passive have become purely arbitrary ones, but, although misnomers if taken in their literal sense, the meaning is sufficiently clear to all students of grammar. The passive voice1 is used when the interest centers upon the subject of the sentence as the objective of the action expressed by the verb, or when the relation between the verb and its thought-object is stressed.2 Thus in the sentence: ‘My son was killed yesterday’, the thought-subject is not even expressed, so important is the connection between the thought-object ‘my son’ and the verb. If, however, the interest were in the perpetrator of the crime, the sentence might be: ‘That man killed my son’. For this form of the verb, the term active has come to be used. The addition of the agent or the means of the action gives the sentence a slightly different emphasis, but if the chief interest is still on the thought-object, the verb retains its passive form: ‘My son was killed by a freight-train (by his brother, etc.)‘. It should be noticed that the passive is more frequently used without the agent, the interest being entirely centered on the thought-object of the verb, i.e. the subject-passive. In many instances where the passive is used, the thought-subject is unknown.