One 45 inch shoot-through umbrella, fabric at 18 inches (its nearest center point was 18 inches).

Essentially it is the same as the softbox (both are 40 inch size at 18 inches). One egg from the first 1 Direct and from this 3 are enlarged below. The egg shell texture is minimized (no shadows to show it), and especially notice how the light wraps around the left dark end of the eggs (more than in 1 because 3 is large, and more than in 4 and 5 because 3 is close). Imagine this contour was a nose or chin or cheek on a face. This "wrap around" is what soft light is, and large and close make it happen.

And this is just one light. Two umbrellas can essentailly eliminate all shadows. A second fill umbrella near the lens axis really helps minimize wrinkles.

Catchlight reflections in human eyes will look different from umbrellas and softboxes. This eye picture is with a reflected fill umbrella at 4 feet. It is not normally viewed this large, and it is hard to see the detail at any regular size. However, shoot-through makes it closer and larger to exaggarate it. A softbox catchlight is rectangular, which we imagine to look like a window reflection.