Rene DesCartes

Something cannot arise from nothing,
and what is is more perfect cannot arise form what is less perfect...
I clearly understand that there is more reality in an infinite substance than in a finite one,
and hence that my perception of the infinite, that is God,
is in some way prior to my perception of the finite, that is myself.
For, how could I understand that I doubted or ...lacked something
and that I was not wholly perfect, unless there were in me some idea of a more perfect being
which enabled me to recognize my own defects by comparison?

Traditional Moral Theory and the Problem of the Practicality of Reason
Wyner, Garret: Toward a Phenomenogy of Conscientious Action and a Theory of the Practicality of Reason:

Life of DesCartes
Philosophy Preceding Descartes in the 15th-16th Centuries
The Cogito ergo sum: Its Nature and Meaning
Malebranche
Spinoza

Early Writings
Rules for the Direction of the Mind
The World
Treatise on Man
Discourse on the Method of Rightly Conducting the Reason & Seeking the Truth in the Sciences
Optics
The Principles of Philosophy
Description of the Human Body
The Passions of the Soul
Meditations on First Philosophy
Objections and Replies
Letters
The Search for Truth

Primary Sources:
Descartes Philosophical Writings (Selected and Trans. by N. Kemp Smith 1952)
The Philosophical Works of DesCartes (trans by E.S. Haldane and G.R.T. Ross, 1911-12)
The Method, Meditations and Selections from the Principles of DesCartes (trans J. Veitch, 1890)
The Philosophical Writings of DesCartes (trans Cottingham, R. Stoothoff, D. Murdoch, 1984)

Some Secondary Sources:
Gibson, A.Boyce: The Philosophy of Descartes
Gordy, J.P.: DesCartes and His School, 1887
Broad, C.D.: Article in Cambridge Historical Journal, 1944
Smith, Norman Kemp: Studies in the Cartesian Philosophy
Smith, Norman Kemp: New studies in the Philosophy of Descartes