What is the Importance of the Substances used in Ritualistic Worship?

The special feature of the series of Holy texts ‘What do Dharmashastras say and why?’ containing the Divine knowledge obtained from God, is that, besides explaining the subtle Science of Spirituality in various religious acts, they also mention the proper methods of performing them. If the scientific reason underlying each religious act is known, it will help attract the present younger generation towards Spirituality.