Definition of "Lens" :

noun: a transparent optical device used to converge or diverge transmitted light and to form images

noun: electronic equipment that uses a magnetic or electric field in order to focus a beam of electrons

noun: biconvex transparent body situated behind the iris in the eye; its role (along with the cornea) is to focus light on the retina

noun: (metaphor) a channel through which something can be seen or understood

"The writer is the lens through which history can be seen."

noun: genus of small erect or climbing herbs with pinnate leaves and small inconspicuous white flowers and small flattened pods: lentils