For the injury caused by the non-performance of most contracts the primary if not the only remedy of the injured party is an action for damages for the breach. In fixing the amount of these damages, the general purpose of the law is, and should be, to give compensation: - that is, to put the plaintiff in as good a position as he would have been in had the defendant kept his contract.1 In some cases this rule of law enables the court to fix with mathematical exactness the amount of a plaintiff's recovery, as in an action on negotiable paper or in other lLord Atkinson in Wertheim v. Chiooutimi Pulp Co.  A. C. 301, 307; Parke, B., in Robinson v.
Harman, 1 Ex. 850, 855; Federal Wall Paper Co. v. Kempner, 244 Fed. 240, 243.
cases where there is a unilateral obligation for the payment of a liquidated sum of money; but frequently the jury must estimate under proper instructions from the court the amount which the plaintiff should receive. The principle of compensation though now definitely established was not that recognized in the early law. In the first place the amount of damages seems to have been in the control of a jury even where the contract called for a liquidated sum;2 but the contrary principle is now well established. The measure of damages is subject to rules of law which cannot be disregarded by the jury.3 It also seems to have been the theory upon which recovery was allowed in the early law in assumpsit that the damages were based on the consideration given rather than on the value of the defendant's performance.4 Such a rule was natural when assumpsit was regarded as in the nature of a tort, and when therefore it might well seem that the law should put the plaintiff in as good a position as he was in before the contract was entered into rather than in as good a position, as he would have been in had the contract been carried out.