Large astronomical structures such as galaxies evolve from primitive initial conditions in the early Universe. In their most general form these initial conditions consist of density, kinematic, and composition inhomogeneities, existing jointly or separately in an otherwise homogeneous universe. Growth and damping mechanisms are considered within a cosmological framework that assumes that density and temperature both increase as we go back in time. From various points of view: long-range interactions, coherent fluctuations, statistical fluctuations, and by invoking causality, it is argued that within the limitations of our knowledge there are persuasive reasons for thinking that the inhomogeneities are imprinted in the Universe from the earliest moment of its expansion.