Popper's ideas can be illustrated further by Antony Flew's Parable of the Gardener, in which two men walking in the forest come across a plot of land, and one of the men thinks that a gardener must tend to this plot, and the other disagrees. They watch for the gardener, but they never see one, so the believer says that he must be an invisible gardener. They put up a fence and guarded it with blood hounds, but there was still no sign of the gardener. The believer still insists that there must be a gardener, who cannot be seen, smelt or heard. Flew's parable is used to demonstrate the idea that a believer in God will not accept any evidence to falsify their belief, and if you argue that a gardener cannot be seen, heard, felt etc, then nothing will remain of your original assertion, and therefore, such statements are meaningless, as they fail to meet the requirements of the falsification principle. Flew says that the concept of God 'dies the death of a thousand qualifications'