It seems equally intuitive that investment drives the economy. The economic principle you're looking for is "velocity of money". If you think of a GDP in terms

It seems equally intuitive that investment drives the economy. The economic principle you're looking for is "velocity of money". If you think of a GDP in terms of a multiplier in how often/fast money circulates, then you can analyze whether investment or spending is more important. The second economic principle to look into after that is "marginal propensity to consume".