Jesus and the Father are easy to grasp because Jesus was born into our world and he told his disciples that whoever had seen him had seen the Father. As to the Holy Spirit, I had difficulty in relating to him in the early days of my spiritual journey. Finally, as I experienced him, I felt comfortable and fell in love with him. He is easier to feel than to describe ~ all I can say is that he conditions my heart and forms my conscience, and is the source of my spiritual joy. When you are in union with him, you know you are in union with God, the Holy Trinity.