Don't aggravate the tension !

"North Korea", we were recently told on BBC News, "has been asked to avoid aggravating the tension".

And a very sensible request that is, for the aggravation of tension is a nonsensical mixture of metaphors that we should certainly avoid.

True, both metaphors are from physics: but tension is the stress of pulling - what the rope experiences in a tug-of-war; while aggravation* is a metaphor from putting on weight - the last straw that breaks a camel's back, as it might be. You can increase tension, but not add weight to it.

* 'Aggravate' derives from Latin ad- (implying here 'increasing') and gravis (meaning 'heavy'). 'Tension' derives from Latin tendere (meaning to 'stretch' or 'strain' something).

Don't aggravate the tension !