The concert started with a “little night music” but expanded into a grand amount of genius. The San Antonio Symphony concluded its part of the Mozart Festival on Friday night with two, really three, of Wolfgang Amadeus Mozart’s late, brilliant masterpieces. The concert’s first half finished with the first of three extraordinary symphonies, No. 39, that Mozart composed in the summer of 1788. The orchestra revved up nicely for the brisk, contrapuntal finale. All of above, though, seemed to wash away when the orchestra jumped into Symphony No. 41, “Jupiter.” The first movement astonished with layered orchestrations that spanned three octaves. The slow movement seemed to pull aside a curtain to reveal an unexplored realm of existence never before imagined. So it was Friday night. The finale topped everything, though, as five melodies dashed hither and yon, eventually meshing for an amazing, enthralling summation that reached the pinnacle of form and content and pleased the audience at the Tobin Center for the Performing Arts.