Nothing captures the power of spatial thinking better than one component of the dead reckoning system, known as etak. Gladwin (1970, p. 181) describes etak as an abstraction:
… of a rather high order. The concept in etak of a specific but invisible island moving under often invisible navigation stars is not only an abstraction. It is also a purposefully devised logical construct by the use of which data inputs (rate and time) can be processed to yield a useful output, proportion of the journey completed.
While that description is analytical and framed to meet our technical understanding of cognitive processes, the remarkable nature of etak is best captured by these passages from Gladwin’s book:
Picture yourself on a Puluwat canoe at night…. On either side of the canoe water streams past, a line of turbulence and bubbles merging into a wake and disappearing in the darkness. Overhead there are stars, immovable, immutable. They swing in their paths across and out of the sky but invariably come up again in the same places. You may travel for days on the canoe but the stars will not go away or change their positions aside from their nightly trajectories from horizon to horizon. Hours go by, miles of water have flowed past. Yet the canoe is still underneath and the stars are still above. Back along the wake, however, the island you left falls farther and farther behind, while the one toward which you are heading is hopefully drawing closer. You can see neither of them, but you know this is happening. You know too that there are islands on either side of you, some near, some far, some ahead, some behind. The ones that are ahead will in due course fall behind. Everything passes by the little canoe—everything except the stars by night and the Sun in the day. (Gladwin, 1970, p. 182)
Thus, the canoe and the sky are seen as fixed in relation to each other: the world is seen as moving or flowing past the canoe. To track the canoe’s position in this moving world requires an etak island (Figure 6.4).