Begin by imagining a square piece of paper. Now fold it into quarters, all the folds are horiontal. Now unfold the paper, yielding 4 long horizontal layers, separated by 3 folds.
Now take the upper left corner and fold it diagonally until it matches up with the upper fold, effectively covering 1/16th of the square piece of paper. Then, we do the same fold, pivoting along the new corner that is aligned with the upperfold, turning the 45 degree turn relative to the fold to 22.5 degree turn (halving it). That will also incidentally line up the corner side to the fold. Now, fold the the upper quadrant along the fold entirely. Turn this 180 degrees and repeat for the other half.
What you have in your mind now is a shape which is half the size of the original square, with a trapezoidal shape on other corner making a diagonal. Now fold the thicker portion of each section to create a triangle that lines up with the opposite side. Now tuck each of those sides under the diagonal flaps. You have just imagined the construction of a unit origami!
I just drew a diagram, in your mind!