sun shining its light on the whole earth. So also you have the one conscience shining its light on all from within. It is the inner sun.
The most important things in life are nothing that can be seen by the eyes. Breath is not usually visible, but without it there would be no life. That is why it is important to try and understand the invisible. You can't see your conscience but you can feel it. That is just as good as seeing it. So anyone who can feel conscience must realise that conscience is real.
The truth is a double edge sword. When one who is seeking it hears it, that one takes delight in hearing it. But to the ears of one who is negative