It would not be admissible therefore to scan:
Love, thát livéth | and réigneth ín my thóught, Surrey, p. 12.
but:
Lóve that líveth | and réigneth ín my thóught.
The licence of displacement of accent is an offence against the fundamental law of accentual verse, and therefore becomes more and more rare as the technique of verse becomes more perfect.
§ 86. Another metrical licence, which is not inadmissible, is the absence of a thesis in the interior of a line. This licence is not of the same origin in Middle English as in Modern English poetry.
In Middle English it generally appears to be a relic of the ancient alliterative verse (Types C and D) and to be analogous to the similar usage of the contemporary Middle English alliterative line, as e.g.:
Ne léve nó mán to múchel | to chílde ne to wíue.
Moral Ode, line 24.
Þet ís al sóth fúl iwís. Pater Noster, 2.