Here is the evolution history of 之: (image taken from http://vividict.com)
|Learn one Chinese Character a day - 之|
Now it is clear that its Oracle Script is composed of (止 - foot) with a horizontal line (- under foot, it refers to earth). With these information, then we can start to guess its meaning. which is 之, orignally means the place where the foot stands. Eventually 之 is used as Pronoun: him or her for any person, or it for anything. And 之 is also used as Modal Particle (https://en.m.wikipedia.org/wiki/Modal_particle), which does not have really any meaning except helping to pronounce a sentence more smoothly.
Let us enjoy a Chinese calligraphy with 之 inside to end our lesson today: