The first pic is an Enso. It is the circle of Zen that points to completeness and the unlimited power of your pure nature/mind. Quantum physics uses this to display the vacuum field of unlimited potential...same thing. This is the Ku/Kara of Karate.
Sanchin Dachi is a Living Enso. It represents unlimited power and potential. It is the 'emptiness is form, form is emptiness' of Zen. With over 40 years of doing this stance, I 'feel it'...and it is awesome. From here, I feel I can defend myself easily. The Ki, or energy, that flows up from the feet and through my body and hands is...well, no words capture it other than 'cool'.
Remember the post on Sanchin with the number 3, for 3 Battles? Three also represents infinity. It is more than two and stretches forever...Combining these two you can see, hopefully, how Sanchin shapes up to be a Kata of unlimited power and defense. You can't get it with your thoughts or feelings, only practice. So practice, practice, practice.
Hands palm to palm,