The Greek mathematician Euclid stated the basic axiom that the whole is equal to the sum of its parts, which is clearly true for everyday geometry, mathematics and science. But when one gets into the realm of the imagination, the arts and other intangible activities, then many people believe that the whole (eg a finished painting) is greater than the sum of its parts (eg the canvas, paints etc).
'Synergy' is the word that means the condition in which
the whole is GREATER than the sum of the parts. This is especially applied in medicine, where individual drugs might be partially effective in treating a condition - eg one may be 20% efficient and the other 30% - but COMBINING the two produces an effect which is, say, 80% effective rather than just 50%.