"Helps by the Way. No. 8. The Greek Prepositions." by Charles H. Welch
in The Berean Expositor circa 1914-15.

En. -- We have considered the prepositions eis (into), and ek (out of),
and the preposition en (in) completes this set of three related
particles.

The primary signification of en is the result of the action suggested
by eis, and indicates the place of rest.  The meaning of the
preposition is modified according as the usage indicates place, time,
agency, &c.

PLACE is the simplest significance, and is nearest in meaning to the
primary idea of the word, as "In the heart of the earth" (Matt. xii.
40).  Sometimes en may be rendered "on," as Rev. iii. 21, "on the
throne"; 2 Cor. iii. 3, "in tables of stone."  The idea of proximity or
nearness is conveyed by this preposition.  "At the right hand of God"
(Rom. viii. 34); "on the right hand" (Heb. i. 3).  Many times en is
best translated by "among"; cf. I Cor. ii. 6, and Col. i. 27, "among
the Gentiles .... Christ among you."

TIME is indicated by this preposition, expressed in English sometimes
by in (Matt. ii. 1), sometimes by on ("on a certain day,") sometimes by
at ("at His coming," "at the last trump"), sometimes by within, e.g.,
John ii. 19.  En ho indicates "in the time that," and is well rendered
by the English "while" (John v. 7; Mark ii. 19).  Those who sinned "in
law" (Rom. ii. 12) are considered as being within its sphere (place)
during its time of operation (time).  Among the more important usages
of en are those indicating:-

AGENCY. -- "through the prince of the demons" (Matt. ix. 34); "With
what measure ye mete" (Matt. vii. 2); "Burn her with fire" (Rev. xvii.
16).

The use of en in the N.T. is sometimes equivalent to the Hebrew use of
beth. Where the Greek authors would employ the Dative case alone to
signify the cause or instrument, the New Testament writers followed the
Hebrew, for example, Patnxomen en machaira(i), "Shall we smite with the
sword" (Luke xxii. 49).  Katapatesosin autous en tois posin auton,
"Lest they trample them under their feet" (Matt. vii. 6).  See also
Rom. xv. 6; Luke i. 51; and Mark xiv. 1.

PRICE. -- A further example of Hebraism is the use of en to denote the
price of a thing (cf. Rev. v. 9 with I Chron. xxi. 24).

PARTNERSHIP. --  "A man with an unclean spirit" (Mark v. 2).  "Shall I
come with (en) a rod, or in (en) a spirit of meekness" (I Cor. iv. 21),

There are many more examples of the figurative usage or secondary
meaning of this preposition which the student is urged to search out
for himself.  There are also some suggestive combinations which will
repay careful study, such as "At home" (2 Cor. v. 6), endemeo is
literally, "among one's own people." "Glorious" ( Cor. iv. 10; Luke
xiii. 17), endoxois is literally "in glory." "To work effectually,"
energeo is literally to "energize" or "inwork" (see Eph. ii. 2; iii.
20; 2 Thess. ii. 7).  "To think on" (Matt. i. 20), enthumeomai is
literally "to have in mind."  "Thoughts and intents" (Heb. iv. 12),
enthumesis  ennoia is literally "the things in the mind (passions,
etc.), and in the mind" (understanding).

The reader can multiply examples and should tabulate his findings in
such a way that they may be of service in after study.