From the
Online Etymology Dictionary:
methinks
O.E. me thyncth "it seems to me," from me, dat. of I, + thyncth, third pers. sing. of thyncan "to seem," reflecting the O.E. distinction between thyncan "to seem" and related thencan "to think," which bedevils modern students of the language (see think). The two words were constantly confused, then finally merged, in M.E.
From the Oxford English Dictionary:
think, v.1 (Old English thyncan) "to seem, appear"
In Old English, as in the cognate languages, the forms of this verb and THINK v.2 remained quite distinct; but in Middle English, owing to the fact that both thync- and thenc- gave ME. think-, ...they became confused and finally fell together. The contiguity of sense also helped: see THINK v.2:
think, v.2 (Old English thencan) "to conceive in the mind, exercise the mind"
In Middle English, thenk (as was normal with the groups -eng, -enk) became think, with the result of confusing this in the present stem with the preceding verb., ...so that the forms of the two verbs became completely identical. The practical equivalence of sense between me thinks, him thought, etc., and I think, he thought, etc., also contributed to this result, there being no difference of import between ‘such compani as him thought [= OE. him thúhte] competent’ (see THINK v.1 B. 2a) and ‘such company as he thought [= OE. he thóhte] competent’.
Methinks ("it seems to me") was becoming obsolete.
In I Cor. 4:9, the KJV translators, like the Geneva translators did a half century before, kept the verb form "think" but used the more common (by then) nominative pronoun "I".
Tyndale: "me thinketh"
Geneva: "I think"
KJV: "I think"
NIV: "it seems to me"
However, in Acts 25:27 the translators retained the dative pronoun and used the verb "seem" instead.
Tyndale: "me thinketh it unreasonable"
Geneva: "me thinketh it unreasonable"
KJV: "it seemeth to me unreasonable"
NIV: "I think it is unreasonable"
