ADVERB CLAUSE-CONTINUED.
+Introductory Hints+.—If it rains, the ground will be wet. The adverb clause, introduced by if, assigns what, if it occurs, will be the cause of the ground's being wet, but, as here expressed, is only a +Condition+ ready to become a cause.
He takes exercise that he may get well. The adverb clause, introduced by that, assigns the cause or the motive or the +Purpose+ of his exercising.
The ground is dry, although it has rained. The adverb clause, introduced by although, expresses a +Concession+. It is conceded that a cause for the ground's not being dry exists; but, in spite of this opposing cause, it is asserted that the ground is dry.
All these dependent clauses of real cause, evidence, condition, purpose, and concession come, as you see, under the general head of +Cause+, although only the first kind assigns the cause proper.
Analysis.
The +adverb clause+ may express +condition+.
1. If the air is quickly compressed, enough heat is evolved to produce
combustion.
2. Unless your thought packs easily and neatly in verse, always use prose.
(Unless = if not.)
3. If ever you saw a crow with a king-bird after him, you have an image of
a dull speaker and a lively listener.
4. Were it not for the warm waters of the Gulf Stream, the harbors and the
rivers of Britain would be blocked up with ice for a great part of the
year.
+Explanation+.—The relative position of the subject and the verb renders the if unnecessary. This omission of if is a common idiom.
5. Should the calls of hunger be neglected, the fat of the body is thrown into the grate to keep the furnace in play.