Moore repeatedly explored the theme of internal/external forms, declaring it one of his favourite subjects. It provided the perfect opportunity to investigate sculptural relationships, generating visual excitement by presenting one form through another. It was the natural development of Moore’s early experiments with piercing holes in his sculpture. He also connected the subject to one of his other much-loved themes – the mother and child:

… this really is an interpretation of the mother and child idea. It is the larger form protecting and having enveloped within it another form, like a child being born. Also, from a sculptural point of view the putting of the form inside another form gives to it a mystery, makes it unable to be explained immediately … If it is obvious then one tends to look at something, recognise it and then turn away, knowing what it is.[1]

As a young artist in London in the 1920s and 1930s Moore was fascinated with the armour in the Wallace Collection, along with New Ireland carvings at the British Museum depicting figures within figures (employing a sort of exoskeleton). These experiences inspired him to investigate the relationship between internal and external space and mass in his sculpture. Moore’s widening exploration of the theme is demonstrated by drawings from the late 1930s which feature full-length figures. Two sheets of studies, both titled Standing Figures (HMF 1494 and HMF 1495), show hollowed-out bodies – the skeletal structures within revealed through numerous apertures similar to those Moore employed in his helmet-related works. Indeed, the drawings recall those of his helmet heads, but here the forms are stacked on top of one another and elongated to create assemblages reminiscent of totem poles. The figures also owe a debt to Moore’s enduring fascination with natural metamorphosis.

The relationship to natural forms is clearly seen in the earlier iteration of this work, Upright Internal/External Form, which was cast in bronze in 1952-53 and stood at just over 2 m high (LH 296).[2] At just over life-size, the scale of the forms is familiar, and relatable to our own bodies. Unlike the Helmet Heads, Moore allowed this work to develop in a decidedly organic direction, emphasising the procreative connotations of the theme. The skeletal figures from the earlier drawings have given way to a fleshy, uterine pod. Moore also noted the affinity between these upright forms and seed pods, or the stamens of flowers, further evoking notions of embryonic growth. The outer shell or encasement reaches around the vulnerable internal figure. It is not only protective but elastic, its shape seemingly determined by the growing forces within. The internal figure is invested with a dynamism of its own, turning and stretching upward, creating an interdependence between core and shell.

In 1981-82, Moore created the monumental Large Upright Internal/External Form. At almost 7 m in height, it soars above the viewer, now appearing both natural and alien, perhaps regaining something of the sinister semi-obscurity that characterises the early Helmet Head sculptures. At this time, Moore also decided to cast the internal figure to stand alone as a work in its own right, simply titled Interior Form (LH 296a).