In so far as the verbals (infinitive, gerund, and participle) make up a part of the English verb system, they have some features in common with the finite forms, and in so far as they are singled out amid the forms of the verb, they must have some peculiarities of their own. Let us first consider the system of verbal categories which are expressed in the English verbals. They have some of them, and they lack some others. We must also observe that it is by no means certain in advance that all the verbals are in the same position as regards the verb categories. It is clear that none of the verbals has any category of person or mood. The English verbals have no category of number either, though this is not so in some other languages. What we must examine is the categories of aspect, tense, correlation, and voice. With reference to aspect we shall have to examine each of the verbals separately. In the infinitive, we find an opposition between two sets of forms: (to) speak — (to) be speaking (to) have spoken— (to) have been speaking, which is obviously the same as the opposition in the sphere of finite forms between: speak — am speaking spoke — was speaking etc. The conclusion here is quite obvious: the infinitive has the category of aspect, viz. there is a distinction between the common and the continuous aspect. The continuous infinitive is found, for example, in the following sentence: He seems to be enjoying himself quite a lot. (R. WEST) In our next example the continuous infinitive of the verb love is used: I can recollect yet how I loved him; and can dimly imagine I could still be loving him if — No, no! (E. BRONTE) The variant with the simple infinitive would be: I can recollect yet how I loved him; and can dimly imagine I could still love him, if — The difference in this case seems to be that the continuous infinitive gives more prominence to the idea of the continuity of her love, and this is obviously much stronger than the mere statement that love might still be there now. The stylistic difference is thus unquestionable, but there would seem to be also a grammatical difference. The meaning of the continuous aspect is well brought out here, though the lexical meaning of the verb love would seem to go against it.
With the gerund and the participle, on the other hand, things are different. Generally speaking, they exhibit no such distinction. Neither in the one nor in the other do we find continuous forms. Occasionally, however, a continuous participle is found, as in the following sentence from a novel by Jane Austen: The younger Miss Thorpes being also dancing, Catherine was left to the mercy of Mrs Thorpe and Mrs Allen, between whom she now remained. It is not clear here what exactly is added to the meaning of the sentence by using the continuous participle being dancing rather than the usual participle dancing. Be that as it may, this example shows that a continuous first participle is at least potentially a part of the morphological system of the English verb. But this use appears to be obsolete. In the following sentence there are even three continuous participles, with one auxiliary common to all of them: Catherine had no leisure for speech, being at once blushing, tying her gown, and forming wise resolutions with the most violent dispatch. (J. AUSTEN) The word order (the phrase at once coming after the auxiliary being) clearly shows that the auxiliary belongs to all three participles (blushing, tying, and forming). The use of the continuous participles seems to be a means of giving prominence to the fact that the actions indicated were actually happening at that very moment.