Every form (rupa) has an idea (nama) corresponding to it. Again every idea has a sound-symbol that is a word corresponding to it. Conversely, every word is associated with an idea and every idea with a form. Form, idea and word are always associated with one another and by no possible means of analysis can one be separated from the others.
‘For instance, take the form [of a] cow. Its idea is the mental aggregate of all the attributes found in a cow. When we see a cow, her form calls up in the mind the cow-idea and we say audibly or in thought, “It is a cow.” Conversely, if we hear the word cow, when no cow is present before us, the word calls up in the mind the cow-idea and we see in imagination the form [of a] cow.
‘This relation between word, idea and form is obvious. They who know the laws of the spiritual world add to this that words can be made receptacles of spiritual force. The spiritual teacher, they say, communicates spiritual force to a word; then the disciple receives the word from him. The word, containing such force, if repeated by the receiver, makes him perceive not the imaginary but the real form associated with the ideas signified by it.
God in His infiniteness is inconceivable to man. The Devas are His many differentiated aspects looked at from particular standpoints. Each of them is a form and associated with particular ideas. The sages saw them in their deepest spiritual perception, found words symbolizing and expressing as nearly as possible the particular forms of God they saw. When animated with the spiritual force communicated to them by the spiritual teacher and received from him by the disciple and repeated by the latter, these words make him realize the forms of God they symbolize.
Source - January 1904 Prabuddha Bharata Magazine – excerpts from article titled Master and Disciple