These represent & stand fora substitute for actual subjects, experiences and activities. e.g. Traffic lights, railway signals, school bells, songs, slogans etc stand for symbolic expression. Thus symbols and signs stimulate & economize thinking. They tell us at once what to door how to act. 5. Language: It serves not only as a link for intercommunication but also acts as a tool for thinking. It consists of words therefore uses symbols sometimes we use gestures in our language. When one is listening, reading or writing, one is stimulated to think. Language is a most effective & developed tool for the process of thinking.