The tongue represents the organ of speech which speaks in two ways, viz. truth and false. The truth can be compared with light, that illuminates (the knowledge of worldly life and life after death). The false creates darkness (that creates confusion).
[Mahabhuta (five fundamental elements)] The five mahabhuta are akasha, vayu, agni, jala and prithvi (in this order). Their attributes are sound, touch, vision, taste and smell respectively.
The order of mahabhutas mentioned above is important because, starting with akasha, the number of attributes per mahabhuta increases in the above order. This increase in number of attributes is cumulative, i.e., the attribute of the preceding mahabhutas is added to the succeeding one. This process of gunantara vriddhi in mahabhutas is also known as bhutanipravesha