system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What is the purpose of adding -eth to the ending of some verbs in older writings?
gpt
In Middle English, you'd conjugate the verb "to think" like so:

Singular      |       Plural
---------|----------
(I)    think        | (we)   think
(thou) thinkest  | (you)  think
(he)   thinketh   |  (they) think

People just started using 'thinks' instead of 'thinketh' and dropped the 'thinkest' altogether.