The physical act of putting on Tefillin is just a symbol of spiritual communication with the higher power. The Tefillin symbolize the correction that we must make in heart and mind to communicate with the higher power. Putting on Tefillin doesn’t correct in itself; rather, the correction depends on a person’s intentions and actions. And that is how it is with all the physical Mitzvot (commandments); they only come as a reminder that it is necessary to carry out internal acts of correction.