If you start on a positive note, considering that its good, than you will see all good things in that person or concept. Your list of good things will be much longer than the list of bad , which you usually tend to overlook . Its difficult to shake that positive thought.
If you start with the negative thought about something or someone, you start highlighting all the negative aspects and your negative list is bigger and all the positives are overlooked. You started with bad and after quick evaluation, ended up with worst thought for that person or thing or concept.
So where should you start ?
If you have positive thought, start by considering that its a negative thing or person and see if you can find and highlight all the negative aspects . Later you can evaluate for yourself if you still think, the positives are more to overlook all negative .
Similar way, if you have negative outlook for someone or something, start your evaluation with the positive bias and see if you can find all positive aspects and later evaluate if your list of positives is still lower than your previous negative outlook .
You might change your mind , from what you were thinking previously.
