We present a detailed overview of the cosmological surveys that we aim to carry out with Phase 1 of the Square Kilometre Array (SKA1) and the science that they will enable. We highlight three main surveys: a medium-deep continuum weak lensing and low-redshift spectroscopic HI galaxy survey over 5 000 deg2; a wide and deep continuum galaxy and HI intensity mapping (IM) survey over 20 000 deg2 from $z = 0.35$ to 3; and a deep, high-redshift HI IM survey over 100 deg2 from $z = 3$ to 6. Taken together, these surveys will achieve an array of important scientific goals: measuring the equation of state of dark energy out to $z \sim 3$ with percent-level precision measurements of the cosmic expansion rate; constraining possible deviations from General Relativity on cosmological scales by measuring the growth rate of structure through multiple independent methods; mapping the structure of the Universe on the largest accessible scales, thus constraining fundamental properties such as isotropy, homogeneity, and non-Gaussianity; and measuring the HI density and bias out to $z = 6$ . These surveys will also provide highly complementary clustering and weak lensing measurements that have independent systematic uncertainties to those of optical and near-infrared (NIR) surveys like Euclid, LSST, and WFIRST leading to a multitude of synergies that can improve constraints significantly beyond what optical or radio surveys can achieve on their own. This document, the 2018 Red Book, provides reference technical specifications, cosmological parameter forecasts, and an overview of relevant systematic effects for the three key surveys and will be regularly updated by the Cosmology Science Working Group in the run up to start of operations and the Key Science Programme of SKA1.

This article investigates the physical parameters of Athenian democracy. It explores the collective-action problems that these parameters caused and settles debates about them that R. G. Osborne famously provoked. Classical Athens was ten times larger than an average Greek state. Fourth-century Athenians were ten times more numerous. These parameters significantly contributed to the success of Athenian democracy. Athens could field more combatants than almost every other Greek state. With such huge manpower reserves individual Athenians had to fight only every few years. Nevertheless, this huge population also caused collective-action problems. Attica's farmers could not grow enough to feed them. The Athenians never had adequate personnel nor recordkeeping centrally to administer so many citizens over such a large territory. Yet they found effective means at home and abroad to overcome these collective-action problems.