Bricks are considered to be the first material created by human intelligence from the four elements: earth, air, water, and fire. ...The great variet… - Eduardo Torroja

Long before... our techniques of today, men could conceive and build structures adapted to the requirements of resistance... because he had observed... the branches of a tree bending under the weight of fruits and the tensioned cords of strings in which children have rocked from time immemorial...

Even children know that drafting rule is easier to bend flat than across the edges; and... they will not be much surprised if told that for the same width of the rule its resistance is proportional to the square of the thickness and the deflection is inversely proportional to the cube of the thickness. Nevertheless some modern designers seem to be unaware... since they require... beams of such slenderness that they resemble springboards...

[E]xperimental investigation of stresses in a plane structure is of great interest and merit as applied to shells with single curvature (barrel shells, pipes) and to shells with double curvature (domes, etc.). In these structures similar states of stress are produced and can be determined at any point as acting in a plane tangential to the center layer of the shell.