Charles Spurgeon on Heaven Is for Real and other heaven tourism books:
It’s a little heaven below, to imagine sweet things. But never think that imagination can picture heaven. When it is most sublime when it is freest from the dust of earth, when it is carried up by the greatest knowledge, and kept steady by the most extreme caution, imagination cannot picture heaven. “It hath not entered the heart of man, the things which God hath prepared for them that love him.” Imagination is good, but not to picture to us heaven. Your imaginary heaven you will find by-and-by to be all a mistake; though you may have piled up fine castles, you will find them to be castles in the air, and they will vanish like thin clouds before the gale. For imagination cannot make a heaven. “Eye hath not seen, nor ear heard, neither hath it entered the heart of man to conceive” it.
—Cited in The Glory of Heaven: The Truth about Heaven, Angels, and Eternal Life (Second Edition) (Crossway, 2013), 18.