It is hard to imagine a present thought that is not connected to either past or future. On the other hand, how is it that a present thought can rely on two things that do not exist? Could there be points of mutual contact where past, present, and future thoughts are joined together? If the present thought was in contact with the past thought, for example, then either that present thought must actually be a past thought, or else the past thought would have to be in the present. The same is true for the meeting of present and future thoughts. Either the present thought is actually still part of the future, or else the future thought is already a present thought.
When you look at the mind, it seems superficially that past thoughts lead to present thoughts and present thoughts to future ones. But if you examine these thoughts more closely, you will see that none of them truly exist. To formulate the existence of something that has no existence as all is called delusion. It is only your lack of awareness and your grasping that makes thoughts seem to have some kind of reality. If thoughts had any inherent existence in the absolute nature of mind, they should at least have a form, or be located somewhere. But there is nothing.
The Heart of Compassion - Instructions on Ngulchu Thogme's Thirty-Sevenfold Practice of a Bodhisattva - pp 128-9, Padmakara Translation Group - Shechen Publications