In English poetry substitution, also known as inversion, is the use of an alien metric foot in a line of otherwise regular metrical pattern. For instance in an iambic line of "da DUM", a trochaic substitution would introduce a foot of "DUM da".
In a line of verse that normally employs iambic meter, trochaic substitution describes the replacement of an iamb by a trochee.
- To swell the gourd, and plump the hazel shells
Using '°' for a weak syllable, '/' for a strong syllable, and '|' for divisions between feet it can be represented as:
Donne uses an inversion (DUM da instead of da DUM) in the first foot of the first line to stress the key verb, "batter", and then sets up a clear iambic pattern with the rest of the line
- To be, or not to be: that is the question:
- Whether 'tis nobler in the mind to suffer
- The slings and arrows of outrageous fortune'
In the first line the word that is emphasized rather than is, which would be an unnatural accent. The first syllable of Whether is also stressed, making a trochaic beginning to the line.
- Fry, Stephen (2005). The Ode Less Travelled. Arrow Books. ISBN 978-0-09-950934-9.
- Steele, Timothy (1999). All the fun's in how you say a thing. Ohio University Press. ISBN 0-8214-1260-4.
- Adams, Stephen (1997-04-07). Poetic Designs: An Introduction to Meters, Verse Forms, and Figures of Speech. Broadview Press. pp. 17. ISBN 9781551111292.
The dictionary definition of anaclasis at Wiktionary