सङ्कल्प - Samkalpa - is a Sanskrit word meaning a resolution; a free will or a determination. The word Sankalpa itself means good intention, an oath or a resolution to do something, a solemn pledge to do something good.All Yagnas and worships are accomplished after taking a vow for its performance. Sankalpa is nothing but an expression of feeling which the Saadhaka (doer) has for accomplishment of a Saadhana (task). By making a pledge a person becomes committed towards the accomplishment of his goal. Taking sankalpa as also oath means becoming committed to something and making Paramatma /Ista-Devata witness of it.
The sankalpa, which we say is in all pujas /rituals at the start, consist of four sections together to announce four important things.
संकल्पो वाव मनसो भूयान्यदा वै संकल्पततेऽथ मनस्यत्यथं वाचमीरयति तामु
नाम्नीरयति नाम्नि मन्त्रा एकं भवन्ति मन्त्रेषु कर्माणि ||१||
Will is greater than the mind.For one wills ,then he reflects , then
he utters speech , and then he utters it in Name. In the Name the
mantras become one ; and in the mantras sacrifice become one.
The examples of the power of the will (Samkalpa) are given in next mantra.
तानि ह वा एतानि संकल्पैकायनानि संकल्पात्मकानि संकल्पे प्रतिष्ठितानि
संकृप्तां द्यवापृथिवि संकल्पेतां वायुश्र्चाssका शं च संकल्पन्तां
ssपश्र्च तेजश्र्च तेषां संकृप्तयै वर्ष संकल्पते वर्षस्य संकृप्त्या
The Heaven earth willed ; the air and Akasha willed ; the water and
fire willed. Through will of these , Rain wills ; through the will of
Rain food wills ; through the will of the food the Breath
wills.through the will of breath Mantra wil; Through the will of
Mantra sacrifice will.Through the will of sacrifice the world wills
through the will of the world , all things will , this is will
meditate upon will .
In the beginning the of Brahman itself created the Sankalpa ,he created this universe through Sankalpa only . And his all the elements which were helpful in his creation also made Sankalpa. That's why we do sankalpa in the beginning of any work. And this is the power of Sankalpa.