Notes:
The left picture is a simulation of light traveling through the universe. The picture shows that the light from distant galaxies (blue) may not encounter a very massive cluster, but because there are mass structures in the universe (orange), the light will be bent all along its path to a waiting observer.
The right picture (another simulation) illustrates what an observer sees on the other end; multiple images of galaxies (blue) elongated along the direction of large-scale, filamentary mass structures in the universe.