the decisions must be understood with this limitation ; for , certainly , no court of last resort will be willing to declare that any and every purpose which the legislative might happen to designate as a public use shall be conclusively held to be so , irrespective of the purpose in question and of its manifestly private character blackstone in his commentaries on the english law remarks that , so great is the regard of the law for private property that it will not authorize the least violation of it , even for the public good , unless there exists a very great necessity therefor .