From the book "Basic teachings of the great philosophers" by S.E. Frost, page 41 (a quote from Immanuel Kant): "Always act so that you can will the maxim or determining principle of your action to become universal law; act so that you can will that everbody shall follow the principle of your action." This is called the "categorical imperative". I don't understand the meaning of "you can will". Does anyone have any idea?