Whenever we are to leave for an auspicious work or a shubh karya or whenever we have to leave for an exam, job interview or any test, we will always find our mothers standing at the threshold of the house with a bowl full of sweet curd and a spoon in her hand, the spoon being scooped with curd and in the position to be put into our mouth as soon as we reach to go out.
This tradition has been a consistent practice amongst Indian mothers and grandmothers who eagerly wait for their child to come at the doorstep and leave for the shubh karya or the exam.
As per shastras, curd and sweet things are considered to be mangalkaari or auspicious. The presence of sweet things is considered customary on the day of festivals so as to invoke an all day auspiciousness in the house.
Curd is formed from the milk which is said to be an elixir for life. The curd is enriched with the properties of the milk.
As per the ayurvedic literature, Curd is considered to be cool and nutritive in nature. It has a calming effect on the digestive system. It cleanses the stomach and aids the memory to be in the mode of attention and serenity.
The sugar, as well being sweet and nutritive has a high energy output. On the day of an auspicious work, the mind is very much preoccupied and tensed as well. This creates pitta in the body which is not conducive and creates body heat and troubles in the digestive system. The tension and anxiety for the exam creates a sort of discomfort in the stomach as well as the mood.
Therefore, in order to relax the whole body, the custom of curd and sugar heaps the best benefit.