It remains to be said that we can deliberately cultivate a mood by concentrating upon it, and thus can predispose the mind to certain associations of thought, so that whatever may turn up in the world or in the mind will lead on to our purpose. This is the way in which concentration leads to success in our chosen vocation or avocation. It makes almost everything you meet a co-worker of yours. Things coming within your purview are polarized by this, so that your experience is unified and you gain both knowledge and power. Or, if you have several purposes or pieces of work, you can turn from one to another when necessary with clear-cut precision by switching over your mood.
I will now give an exercise in the polarization of thought: