A friend who has spent time in court told me about evidence. If a witness describes what he or she heard second hand, the judge will throw it out. 

"Hearsay."

There is a substantive difference, legally speaking, between watching a thief run by, and retelling what you heard about it.  

My friend compared it to walking on the nature trails near his home. 

"I have some great maps and books with pictures, showing the foliage and birds. It is easy to stay on the couch and read about them. I have my snacks beside me, and I'm sheltered from the weather. But going out the door to ramble under aspen boughs, and listen to the crunching leaves, is better."

Another friend at the table has walked the Grand Canyon, rim to rim. I saw the photos. But even with his enthusiastic stories, I don't understand what it was like. All I have is hearsay. 

Being a spiritual man, the first man compares it to our inclination to study scripture. Being able to repeat the events of The Good Samaritan is a step removed from showing up with comfort and a strong shoulder. A step in the right direction, some would say.