The golden cup is I suppose the Truth-Consciousness.

The Divine Consciousness we are trying to bring down is a Truth-Consciousness. It shows us all the truth of our being and nature on all the planes mind, life and body. It does not throw them away or make an impatient effort to get rid of them immediately and substitute something fantastic and wonderful in their place. It works upon them patiently and slowly to perfect and raise in them all that is capable of perfection and to change all that is obscure and imperfect.

Yes, of course, complete truth of speech is very important for the sadhak and a great help for bringing Truth into the consciousness. It is at the same time difficult to bring the speech under control; for people are accustomed to speak what comes to them and not to supervise and control what they say. There is something mechanical about speech and to bring it to the level of the highest part of the consciousness is never easy. That is one reason why to be sparing in speech is helpful. It helps to a more deliberate control and prevents the tongue from running away with one and doing whatever it likes.