Blaise Pascal, mathematician and philosopher, said The heart has its reasons of which reason knows nothing. He was not talking of love, but of first principles; perception of space, time, motion and number. It is the heart that teaches us the foundations of geometry.
It is just as pointless and absurd for reason to demand proof of first principles from the heart before agreeing to accept them as it would be absurd for the heart to demand an intuition of all the propositions demonstrated by reason before agreeing to accept them.
Baruch Spinoza believed that life was of two kinds; human bondage, or, slavery to our passions, and, human freedom, or, liberation by our intellect. Human beings wrongly believe themselves to be making free, undetermined choices; because we do not know the causes of our choices, we assume they have none. The only true liberation possible for us is to make ourselves conscious of the hidden causes.
For Spinoza, passive emotions, like fear and anger, are generated by external forces; active emotions arise from the mind's understanding of the human condition. Replacement of passive emotions by active ones is the path to liberation. In particular, the passion of fear, including the fear of death. The key to progress is the appreciation of the necessity of all things. Spinoza believed that when we realise the acts of others are determined by nature, we cease to feel hatred. Returning hatred only increases it, but reciprocating it with love vanquishes it. What we need to do is take a 'God's-eye-view' of the whole necessary natural scheme of things, seeing it in the light of eternity.
This and his equation of God as Nature (Deus sive Natura), are close to Eastern philosophical thought. Although ambiguous (and often debated), this 'God' is taken to mean, not some 'incorporeal substance' who directs things from on high, but the whole natural, self-ordering system, whose code we can never fully know. I prefer this idea; is this not relevant now, when we are treating technology as a kind of God who we think we can know and control? Must not this idea of life remain ambiguous and unknowable? I remember something from Dostoïevski, will we not devise eventually a system of perfect order, of perfect paths, that can be consulted at any time, to direct us to right and wrong? And then, will we not still break things, because sometimes, in the light of the consequences, knowing what is best for us and for others, and perhaps for the very fact of this knowledge, we desire to destroy, often the very thing that we love? Perhaps it is this ordering that is our downfall, our hubris to control and 'know' the system. We never can. And is this not more beautiful? Is it perhaps the very essence of this beauty that the experience of the sublime (of knowledge, of understanding) is but a part of the whole, and whole will always remain mysterious?