So we see that the present holding within itself the past and the future exists in reality. For the past though it has been negated has really been preserved and kept in the present, and the future also though it has not made its appearance yet exists potentially in the present. So, as we know the past and the future worlds in the present, they both exist and subsist in the present. That which once existed cannot die, and that which never existed cannot come to be (_nāstyasataḥ saṃbhavaḥ na cāsti sato vināsāḥ_, _Vyāsa-bhāshya_, V. 12). So the past has not been destroyed but has rather shifted its position and hidden itself in the body of the present, and the future that has not made its appearance exists in the present only in a potential form. It cannot be argued, as Vācaspati says, that because the past and the future are not present therefore they do not exist, for if the past and future do not exist how can there be a present also, since its existence also is only relative? So all the three exist as truly as any one of them, and the only difference among them is the different way or mode of their existence. He next proceeds to refute the arguments of those idealists who hold that since the external knowables never exist independently of our knowledge of them, their separate external existence as such may be denied. Since it is by knowledge alone that the external knowables can present themselves to us we may infer that there is really no knowable external reality apart from knowledge of it, just as we see that in dream-states knowledge can exist apart from the reality of any external world. So it may be argued that there is, indeed, no external reality as it appears to us. The Buddhists, for example, hold that a blue thing and knowledge of it as blue are identical owing to the maxim that things which are invariably perceived together are one (_sahopalambhaniyamādabhedo nīlataddhiyoḥ_). So they say that external reality is not different from our idea of it. To this it may be replied that if, as you say, external reality is identical with my ideas and there is no other external reality existing as such outside my ideas, why then does it appear as existing apart, outside and independent of my ideas? The idealists have no basis for the denial of external reality, and for their assertion that it is only the creation of our imagination like experiences in dreams. Even our ideas carry with them the notion that reality exists outside our mental experiences. If all our percepts and notions as this and that arise only by virtue of the influence of the external world, how can they deny the existence of the external world as such? The objective world is present by its own power. How then can this objective world be given up on the strength of mere logical or speculative abstraction?