I'm doing a monthly essay proverb. I wanna know what's the figure of speech in "absent makes the heart forget." ?

I think you mean this one, right?

http://www.google.com/search?hl=en&client=firefox-a&hs=vv1&rlz=1R1GGLL_en___US379&q=absence+makes+the+heart+grow+fonder+origin&aq=2&aqi=g10&aql=&oq=absence+makes+the
Read widely, and let us know what you think.