The Etymology and Syntax of the English Language Explained and Illustrated

by Alexander Crombie

This verb having only one tense, namely, the present, past necessity is expressed by the preterite definite of the verb, significant of the thing necessary, as,

I must have	Thou must have, &c.	}	written.
We must have	Ye must have, &c.	}

Present Liberty.
I may	Thou mayest	He may	}	write.
We may	Ye may	They may	}
Past Liberty.
I might	Thou mightest	He might	}	write.
We might	Ye might	They might	}

Or,
I might have	Thou mightest have, &c.	}	written.
We might have	Ye might have, &c.	}

Present Ability.
I can	Thou canst	He can	}	write.
We can	Ye can	They can	}
Past Ability.
I could	Thou couldst	He could	}	write.
We could	Ye could	They could	}

Or,
I could have	Thou couldst have, &c.	}	written.
We could have	Ye could have, &c.	}

Could, the preterite of the verb can, expressing past power or ability, is, like the tense might of the verb may, frequently employed to denote present time. Of their denoting past time the following may serve as examples.

“Can you construe Lycophron now? No; but once I could.”

“May you speak your sentiments freely? No; but once I might.”