"The senses deceive from time to time, and it is never prudent to trust wholly those who have deceived us even once."
                                                                          --René Descartes

Some would call it frivolouse or wastefull to seek certainty by calling everything into question to see if one can doubt it as Descartes did. Well, it very well could be. However, if you seek to understand with certainty, such questioning becomes necessary. The provisional methods of science and spirituality may suit some just fine. Others seek a deeper understanding.

Neither path is better. The provisional path is more likely to find things quickly. The certain path is more likely to find enduring truth, though slowly.

I have taken the certain path. As such, I had to consider what I could know for certain. Here is what I found:

I do not know any object. Colors, sounds, odors, flavors, tactile sensations, spiritual sensations, ALL sensations and ALL the things I understand through the sensations are ALL uncertain and doubtfull.

All sensation is produced by the mind, just as the pixels on your computer screen are created by software. Such sensations could arise through the contact of various senses with various stimuli stimulating the mind to produce sensation. Or, the mind could simply produce sensation of its own accord.

All sensation is an illusion. You never see a tree. You see colors that form an image in your mind of a tree. These colors arise from the way in which photons of light bounce from the tree to receptors in your eye. Or, maybe your mind simply conjured an image of a tree from experience and imagination.

Without this illusion, we would never even begin to understand a tree. A tree has no color, no odor, no flavor, no qualities whatsoever that the mind could comprehend without sorting it out much like your operating system sorts out what to do with a bunch of ones and zeros to do something usefull

So, this would seem to put absolutely everything into doubt. Even the self, "I", that Descartes thought his certainty becomes doubtful in this light. What then is certain?

I have found one thing. Though we do not know the objects of experience, we do know experience itself. I may not know red, or tree, but when I see red or tree I know I see red or tree. I may not know ideas, but I know thinking. I do not even know I, there is activity though and its convenient to attribute it to something in converstion so as to avoid confusion.

Motion, activity, doing, performance. By doing a thing, we know a thing. This is certain. When you delight in a winter's day, this is certain. When you drink, you breath, think, see, hear, or do anything this is certain.

The point: You can't know any object. What you see, hold, and possess is uncertain and removed from you. Its what you do that matters.