The submission of the appellant is that where the injury of the worker consists of the acceleration of a pre-existing disease not caused by working in the employment, the compensable incapacity is that which results from the acceleration alone: that is to say, that if that disease, unaccelerated by work in the employment, would have at some time caused the incapacity, its acceleration can only relevantly cause that incapacity for the period which elapses between the onset of incapacity and the time at which that incapacity would in any case have occurred. The principal support for this argument is found by the appellant in the judgment of my brother Windeyer in McLaughlin & Co. Pty. Ltd. v. Brinnand [1] . In a general statement of the relevant law, there occurs in my brother's judgment the following passage: "The effect of the Workers' Compensation Act NSW since it was amended in 1960 is in my opinion as follows. If, without any aggravation or acceleration contributed to by his employment, a worker would have become incapacitated to the extent he was and when he was by a disease from which he was suffering, then, whether or not there was in fact any aggravation, acceleration or exacerbation of the disease, his incapacity cannot be said to result from aggravation, acceleration or exacerbation. If, on the other hand, a worker's disease is so aggravated by his employment that it causes an incapacity when without such aggravation he would have suffered no incapacity from the disease, then he is entitled to compensation. And if the effect of the aggravation is to cause a greater degree of incapacity than the disease unaggravated would have done - as, for example, if what would otherwise have been a partial or intermittent incapacity becomes a total or permanent incapacity - he is entitled to compensation for the incapacity actually occurring, for it is the result of the aggravation of his pre-existing condition; and it is immaterial that unaggravated he might still have been to some lesser degree incapacitated. If, however, the employment by aggravating his disease or accelerating its progress merely causes an incapacity of the same degree that the disease would in time have caused but causes it earlier, then it seems to me that the resulting compensable incapacity is only that which can be said to be attributable to the aggravation or acceleration: that is to say, it is the incapacity from its actual occurrence to the time when, ex hypothesi, the disease, if not accelerated or aggravated, would have produced it. It may be that these considerations are artificial in relation to fundamental ideas of medical science. Their application may present special difficulties in connexion with diseases of uncertain aetiology. But it seems to me that the language of the Act forces them upon us. Bearing them in mind, I have reached the conclusion that there was no evidence to support the award in this case of continuing compensation from 1st December 1961."