Chakra Crystals Set - Thymus
The following description of the Thymic chakra is by John ONeill: The Thymic chakra is where intent originates, it is the link between the emotions of the heart and the reason of language. It is what makes you inhale a breath before you speak, since this is where the intent behind the words you are about to speak actually starts forming. So, let's say that your heart feels a certain way about something that it would like to voice, the energy shoots up to the Throat chakra but passes through the Thymic chakra first, giving it a heads up to start getting prepared to speak by drawing a breath - or by stopping the breath to prevent you from speaking. This is why you don't always say what's on the tip of your tongue. This is also why emotions can wreck havoc with your health, as the Thymic chakra can be bombarded by emotions to the point of fatigue.
When the Crown chakra speaks, on the other hand, it sends its energy down through the Brow chakra which embellishes it. The result is creative expression which may or may not be truthful. The Thymic chakra acts as something of a lie detector by interfering with energy that is not truthful. This is why we have trouble speaking when we are upset. The flow of energy from the heart is always meant to be peaceful and that's really the only kind of energy that the Thymic chakra understands.