According to David Hume, why can't past experience justify claims about the future?

We can never observe a necessary connection between events. Why can't past experience justify claims about the future, according to Hume? We can never know whether or not the future will be like the past. ... Because these are preconditions of all possible experience based on the mind's own organizing principles.

Explanation:

photography had emerged as an elite art pursued by a few creative individuals for a few wealthy patrons. but now, said bauldelaire, it was succumbing to "the great industrial madness of our times." it was becoming a mass production industry that catered to middle-class tastes, including a taste for gadgetry. the stereoscope, the first 3d imaging system, had turned looking at photographs into parlor entertainment. a "thousand hungry eyes were bending over the peepholes of the stereoscope as though they were the attic-windows of the infinite.