Lexical Definitions - Imperfect Tense

The imperfect expresses an action, process or condition which is incomplete, and it has a wide range of meaning:

1a) It is used to describe a single (as opposed to a repeated) action in the past; it differs from the perfect in being more vivid and pictorial. The perfect expresses the "fact", the imperfect adds colour and movement by suggesting the "process" preliminary to its completion.

he put forth his hand to the door
it came to a halt
I began to hear

1b) A phrase such as "What seekest thou?", refers not only to the present, but assumes that the search has continued for some time.

Why do you weep?
Why refuse to eat?
Why are you distressed?

These relate not so much as to one occasion, as to a continued condition.

2) The kind of progression or imperfection and unfinished condition of the action may consist in its frequent repetition.

2a) In the present:

it is "said" today
a wise son "maketh glad" his father

2b) In the past:

"and so he did" (regularly, year by year)
a mist "used to go up"
the fish which "we used to eat"
the manna "came down" (regularly)
he "spoke" (repeatedly)

3) The imperfect is used to express the "future", referring not only to an action which is about to be accomplished but one which has not yet begun:

3a) This may be a future from the point of view of the real present; as:

Now "shalt thou see what I will do"
"We will burn" thy house

3b) It may be a future from any other point of view assumed; as:

he took his son that "was to reign"
she stayed to see what "should be done"

4) The usage of 3b may be taken as the transitive to a common use of the imperfect in which it serves for an expression of those shades of relation among acts and thoughts for which English prefers the conditional moods. Such actions are strictly "future" in reference to the assumed point of relation, and the simple imperfect sufficiently expresses them; e.g.

of every tree thou "mayest eat"
"could we know"
he "would" say

5a) The imperfect follows particles expressing "transition", "purpose", "result" and so forth as, "in order that", "lest"; e.g.

say thou art my sister, "that it may be well with thee"
let us deal wisely with the nation, "lest it multiplies"

5b) When however there is a strong feeling of "purpose", or when it is meant to be strongly marked, then of course the moods are employed; e.g.

raise me up "that I may requite them"
who will entice Ahab "that he may go up"
what shall we do "that the sea may be calm"

The moods are also employed to express that class of future actions which we express in the "optative"

"may I die"
"may" the LORD "establish" his word
"may" the child "live"