Full Idea
Since rays of light need time - however little - to reach us, it is possible that the object should be destroyed during the interval and no longer exist when the light reaches the eye.
Gist of Idea
Light takes time to reach us, so objects we see may now not exist
Source
Gottfried Leibniz (New Essays on Human Understanding [1704], 2.09)
Book Reference
Leibniz,Gottfried: 'New Essays on Human Understanding', ed/tr. Remnant/Bennett [CUP 1996], p.135
A Reaction
This is the well know 'time lag' argument. Leibniz is no sceptic, but he can hardly fail to accept the truth of this problem. It seems self-evident that stars we observe may no longer exist, although special relativity confuses that issue.