For example: What is the difference in saying "To err is human" vs. "Making mistakes is an intergal part of the human condition?"

In our textbook "Speak Out C1" the author explains that it is more common for gerunds to be used as the subject of the sentence. However, one of my students told me that a previous English teacher taught that it is better to use the infinitive.

Intunitively I feel that the infinitive form is a little bit more poetic-sounding, but is there actually any difference in meaning?

Are there grammar rules governing the usage of these two forms as the subject of a sentence?

Thank you so much in advance for your help.

  • As noted, To err is human is a fixed phrase, which means it sounds just fine the way it is. It's not a syntactic rule; it's frozen in place like a word. In general, gerunds are more common as subjects, for several reasons, which I go into in this answer. Commented May 25, 2021 at 20:07

3 Answers 3


'To err is human' sounds much better than 'erring is human' because it is a fixed phrase and the lexeme 'err' / 'erred' / 'erring' ... sounds odd in most other sentences. This skews an appraisal of idiomaticity for the general usages. And this questiion involves idiomaticity rather than grammaticality.

These Google ngrams only begin to hint at how much more frequently used sentences beginning with 'Swimming is' / 'Endurance swimming is' etc are than sentences beginning 'To swim is'. Checking on the first 20 examples from the 1996 - 2008 sample interval for 'swimming is' reveals mostly relevant examples, while all the first 20 examples from the 1982 - 2008 sample interval for 'to swim is' are false positives like 'Learning to swim is ...'.

So, while 'To err is human' is the idiomatic (natural sounding) choice and 'Erring is human' sounds smart-alecky or amateurish, only set expressions like

  • To err is human, to forgive divine.

  • To think is to act.

  • To travel hopefully is better than to arrive.

(and perhaps in rare contexts 'to be or not to be'), and examples in formal and especially literary / oratorical registers, sound reasonable; the -ing form variants are far more colloquial (and do occur in at least one fixed expression):

  • Seeing is believing.
  • Growing old is mandatory, but growing up is optional.
  • Smoking is forbidden in the hospital grounds.
  • [Endurance] swimming is a fine way to keep fit.
  • Making mistakes is an integral part of the human condition.

However, sometimes the to-infinitive is the only choice available:

  • 'To walk beside my father down Sixth Street was to hear the asphalt sing.' (John Updike, The Centaur)

The -ing form here would be at best a garden-path invitation, setting us up for a participial clause rather than a subject. But this literary and formal usage works well here.


Infinitives lean more towards abstract/general concepts while gerunds lean towards real concepts but they are often interchangeable just like your example.


Personally, I don't see any difference between "To err is human" and "Erring is human". That's just a matter of word construction and, I believe, rhythm-based.

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