esse est percipi

This is George Berkeley, an English philosopher who believed 'to be is to be perceived'. To further illustrate this motto of him, let's read the story below first.

"One day when Berkeley and his friend were strolling down a garden, the friend accidentally kicked a rock on the path. Then the friend asked: "does this rock ever exist?" Berkeley thought for a while and answered: "the rock only exists when you feel the pain."

.....so, was he trying to say that the rock never exist on the earth if his friend never kicked it? I know this is such a superficial question for a wise man to answer. To make it easier to understand, let's put it into a medical setting:

Let's say Mr. A has pancreatic cancer, no major changes on his body except change of bowel habits. Then he comes to a hospital, does x-ray, MRI, CAT, serum albumin, alkaline phosphatase...you name it. Cannot detect any sign of cancer at all.

Of course Mr. A would not know that he got cancer, as he couldn't perceive any symptoms from the cancer. For doctors, they would not know as well because they couldn't perceive anything from the tests results. Up to this point, Berkeley's quote still works. Let's change the story a bit, says the doctor suddenly feels like doing a biopsy and surprisingly finds out the cancer at its beginning stage. This time Mr. A knows he has cancer based on doctor's evaluation, not what he feels. So he will go back and tells his family that "i have cancer because my doctor told me so", not "i have cancer because i'm not feeling well".

Thus if i tell you a lie, and you perceive it as truth, then something will somehow exists, can i still say "to be is to be perceived"? Duno what am i writing, need some guidance please...