An infinitive phrase can function directly as the subject of a sentence, typically in formal or aphoristic register, as in to err is human, to forgive divine. This differs from the more common pattern with preparatory it, as in it is human to err, though both are correct.
Grammar Rule
An infinitive phrase can function directly as the subject of a sentence, typically in formal or aphoristic register: To err is human, to forgive divine. This differs from the more common pattern with preparatory it: It is human to err. Both are correct, but the fronted infinitive is more formal. When two infinitive subjects are coordinated, keep parallel structure — both sides the same form.
Infinitive with To in Initial Position as Subject: Rules and Examples
| Pattern | Register | Example |
|---|---|---|
| To-infinitive as fronted subject | formal, literary, aphoristic | To err is human, to forgive divine. |
| It + be + adjective + to-infinitive | everyday, especially with long phrases | It is human to err. |
| Parallel coordination | both sides keep the same form | To see is to believe (not to believe / believing mixed). |
Remember: A fronted to-infinitive can be the subject of a sentence, but everyday English usually prefers It + be + adjective + to-infinitive instead.
Practice Test
Instructions
Answer each question in the test below using a fronted to-infinitive as subject correctly. You will get a new random set of questions every time you retake the test, plus a downloadable results summary with your name and score at the end.
C1-25 Infinitive with To in Initial Position as Subject
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Frequently Asked Questions
Can a to-infinitive be the subject of a sentence?
Yes, typically in formal or aphoristic register, as in to err is human, to forgive divine.
What is the more common alternative to a fronted infinitive subject?
The pattern with preparatory it, as in it is human to err.
Which version is more formal?
The fronted infinitive subject is more formal than the preparatory it pattern.
What rule applies when two infinitive subjects are coordinated?
Both sides must keep parallel structure, the same form, as in to see is to believe.