On they flew through the gathering darkness; Harry's face felt stiff and cold, his legs numb from gripping the Thestral's sides so tightly, but he did not dare shift his position lest he slip ... he was deaf from the thundering rush of air in his ears, and his mouth was dry and frozen from the cold night wind.

Harry Potter and the Order of the Phoenix

I don't quite understand the use of 'ON' in the clause above. Is it an adverb or prep.? I feel it's saying while on the way they flew through the gathering darkness. Is my understanding correct?

  • "on" here is a preposition. It is another way of writing "they flew on through the gathering darkness". The sentence gives an impression of continuous flying and intensifying darkness. Apr 19, 2019 at 1:56
  • @EddieKal according to the modern grammar, it is always a preposition. Apr 19, 2019 at 2:26
  • @EddieKal Please refer Cambridge Grammar of the English Language on page 284 near the end, under the heading - Preposing. Apr 19, 2019 at 4:17
  • 1
    @Man_From_India Nice catch! It was the other Huddleston and Pullum 2002 apparently. Found the section. And you are absolutely right about prepositions. Actually pp 272-275 are more thorough in defining these terms and distinguishing their definitions from others'. I stand corrected.
    – Eddie Kal
    Apr 19, 2019 at 4:56

1 Answer 1


It is an adverb.

From Merriam-Webster's definition of on:

2 b : in continuance or succession
// rambled on
// and so on

In the sentence in question:

on they flew
→ they flew on

The adverb is then followed by the prepositional phrase through the gathering darkness.

  • It seems to be an inversion. I'm wondering what purpose of the inversion is?
    – dan
    Apr 19, 2019 at 4:35
  • 1
    @dan It's stylistic. Because of the cadence, it sounds more poetic. Apr 19, 2019 at 4:39

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