- To remain ignorant is to remain a slave.
To remain ignorant, is the subject of the copulative verb is, and the infinitive, to remain, with its complement, a slave, is the predicate complement.
433. A participle used as a noun may also be used as the predicate complement, thus:
- Society is the mingling of many elements.
Mingling, in this sentence is a participle of the verb mingle, but is used as a noun, the predicate complement of the verb is. Society is the subject of the verb.
Where the present participle is used to form a verb phrase, the participle is part of the verb phrase, thus:
- We are mingling in society.
Here, are mingling, is the present progressive verb phrase, and the participle mingling is not used as a noun or adjective, but is part of the verb phrase are mingling.
If you will observe the different parts of speech carefully, you will not be easily confused as to whether the participle is a noun or a part of the verb phrase.