(after stating the facts as above). If a duty rests upon a public service corporation to afford facilities independently to each of two persons, industries, or localities, the service 'must be rendered on substantially equal terms, impartially, without undue discrimination. But if no duty in law exists to serve either, then the giving to one of what is not owed cannot be a basis for the other’s complaint of unlawful discrimination; that is, back of any question of unlawful discrimination must lie the duty to serve.

[1, 2] It is usually said that a common carrier’s duty is to serve the public. In a general sense this is true, for latently the right to be served is in the public; but the carrier’s duty arises only when some individual demands a service that is common, that is due to him as a member of the public. And if the individual separates himself from the public, and demands a use of the carrier’s property or facilities, not in the common right, but for his own separate profit or advantage, the carrier may either refuse or, within certain limits, obligate itself to give the special privilege. We say “within certain limits,” for in the public interest the carrier cannot be permitted to incapacitate itself for the full performance of its public obligations. These principles are sufficiently illustrated in The Express Cases, 117 U. S. 1, 6 Sup. Ct. 542, 628, 29 L. Ed. 791; Lake Shore, etc., Ry. Co. v. Smith, 173 U. S. 697, 19 Sup. Ct. 565, 43 L. Ed. 858; Donovan v. Penn. Co., 120 Fed. 215, 57 C. C. A. 362, 61 L. R. A. 140, affirmed in 199 U. S. 279, 26 Sup. Ct. 91, 50 L. Ed. 192; Johnson v. Georgia Rld. Co., 108 Ga. 496, 34 S. E. 127, 46 L. R. A. 502; State ex rel. Skeen v. Ogden Rapid Transit Co. (Utah) 112 Pac. 120; 1 Wyman on Public Service Corporations, § 757.

[3, 4] Tested by these principles, a cause of action was neither pleaded nor proved. Plaintiff was not demanding, in the common right, that he be accepted as a passenger. As agent of intending passengers, plaintiff had no standing, for the right would be in them. Further, no group of persons, who separate themselves from the public, can demand, in the common right, that a special train, to which they alone, and not the public generally, shall be admitted, shall be run on such days and at such hours as they choose to Birnam Wood, or any field or grove that pleases them. Still less is there room for the claim that every landowner, or any landowner, who may have rented his ground to intending picnickers, can by mandamus compel the carrier to furnish such trains.

Defendant, a- foreign corporation doing an interstate business, was, of course, as fully subject to Illinois law as any interstate carrier chartered! by the state. But we find nothing in the Illinois Constitution, statutes, or decisions that furnishes any foundation for plaintiff’s case. *351Authorities dealing with the rights-of passengers, shippers, and consignees are not in point, for plaintiff was not a passenger, nor was he a shipper or consignee of passengers.

[5] Contract and custom were urged in argument as additional grounds of plaintiff’s case. That plaintiff on defendant’s “encouragement” should have opened his park, and] “at defendant’s special instance and request” should have invested so large a sum in structures, may have been unfortunate. But no contract elements of time, terms, conditions, mutuality, appear in pleadings or proofs; and the cause was submitted to the jury solely as one of discrimination. As to custom it is enough to say that a custom to do a thing from time to time tinder special contracts will not establish a custom to dispense with contracts.

The judgment is reversed, and the cause is remanded for further proceedings not inconsistent with this opinion.