So, we had our electrostatic compasses, and we set them near charged objects. We saw some patterns. We quickly agreed that any positive charge would feel a force in the direction the electrostatic compass points. We could see that the direction of the force could be determined anywhere in three-dimensional space. We also could see the force would be weaker in some places and stronger in others. We then could draw these forces for some simple configurations of charges; we called these pictures of many vectors of the direction of the force the electric field. We'll refine this definition as we go on.