By the magical power of "ifs," "buts," "perhaps's," "what do we know," etc., heaped together, a shapeless and unconnected system is formed, perplexing mankind, by obliterating from their minds, the most clear ideas and rendering uncertain truths most evident. By reason of this systematic confusion, nature is an enigma; the visible world has disappeared, to give place to regions invisible; reason is compelled to yield to imagination, who leads to the country of her self-invented chimeras.