Advanced in this paper is a Qur’anic perspective on thinking, rationality, and critical reason, which in its critical and goal-oriented dimensions provides a set of guidelines that ensures its purity and purpose from negative reductionist influences. The guidelines so provided are also rich in advancing a spiritual dimension with the understanding that thinking which is not informed by morality and faith can lose its direction and purpose and can even become harmful to human welfare. The paper begins with a discussion of the divine signs, the ayat, and the prominent profile that they take in the Qur’anic conception of thinking. Other topics discussed include an identification of the sources of knowledge in the Qur’an, factors that impede rational thinking, and a historical sketch of the golden age of scientific creativity and its eventual decline. A brief section is also devoted to ijtihad and where it fits into the scheme of our analysis on thinking, followed by a short comparison of Islamic and Western philosophical perceptions of rationality.