I wonder if we need an indefinite article in front of the word "zest" in a sentence of this kind:
It will certainly add zest to your relationship.
Learn how to add zest to your food.
It is easy to add zest and zing to a living room.
...give zest to...
Dog trained by prisoner gives teen a zest for life
I do not, of course, mean that there are not battles, conspiracies, tumults, factions, and all those other phenomena which are supposed to make History interesting; nor would I deny that the strange mixture of the problems of life and the problems of Mathematics, continually inducing conjecture and giving the opportunity of immediate verification, imparts to our existence a zest which you in Spaceland can hardly comprehend.