The reason is very simple as we can see of objects withing a range of size from some micro seconds to some distance of few kms. If wen need to extend this range we need extra families like microscope or binocular,

Similarly when we want to fell HIS existence and have full faith in HIM we need to purify or spirit. The purification process can start from doing return free service of the community or individuals. Followed by HIS Worship, and meditation. Once a person is able to to these activities with love, faith and affection. HE realizes every day and every moment HIS existence in each activity of his life. And finally he can see HIM and commune with HIM.