I believe most of us would agree that there are many ideas Spinoza expresses in the Ethics which have immediate value in human life both for individuals and for interaction between individuals. For example he points out that Reason shows us:

======== E5: PROP. 41:
Even if we did not know that our mind is eternal, we should still consider as of primary importance piety and religion, and generally all things which, in Part 4., we showed to be attributable to courage and high-mindedness.

Proof.--The first and only foundation of virtue, or the rule of right living is (E4P22C and E4P24) seeking one's own true interest. Now, while we determined what REASON [my emphasis] prescribes as useful, we took no account of the mind's eternity, which has only become known to us in this Fifth Part. Although we were ignorant at that time that the mind is eternal, we nevertheless stated that the qualities attributable to courage and high-mindedness are of primary importance. Therefore, even if we were still ignorant of this doctrine, we should yet put the aforesaid precepts of reason in the first place. Q.E.D.
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    Clearly however, as he states throughout his writing, he is aiming higher than what Reason is able to show. He told us in the TEI and again in several places in the Ethics and elsewhere that it is Intuitive Knowledge of our own particular nature that reveals our minds Highest Blessedness. Whether any of us find this for ourselves or not I do not believe we can ignore Spinoza's expressions that he had found this for himself. In the note to E1P8 he says in reference to E1P7 which shows that "Existence belongs to the nature of substance.":

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"...But, if people would consider the nature of substance, they would have no doubt about the truth of E1P7. In fact, this proposition would be a universal axiom, and accounted a truism."
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    Is he not saying that we can know this directly, through intuition as he defines it? What comes with this kind of knowledge?:

======== E5: PROP. 32:
Whatsoever we understand by the third kind of knowledge, we take delight in, and our delight is accompanied by the idea of God as cause.
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    A bit further on he calls our attention to the difference between Reason and Intuition as it involves this Highest Happiness. He tells us that he discovered this for himself and that, although it is very difficult, he encourages us that we can discover it for ourselves too:

======== E5: PROP. 36 Corollary, Note:
... I have thought it worth while here to call attention to this, in order to show by this example how the knowledge of particular things, which I have called intuitive or of the third kind (E2P40N2), is potent, and more powerful than the universal knowledge, which I have styled knowledge of the second kind. For, although in Part 1 I showed in general terms, that all things (and consequently, also, the human mind) depend as to their essence and existence on God, yet that demonstration, though legitimate and placed beyond the chances of doubt, does not affect our mind so much, as when the same conclusion is derived from the actual essence of some particular thing, which we say depends on God.
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    So in words anyway he recommends Intuition but what does he mean by Intuition and how does it differ from Reason? In both the TEI and The Ethics he uses some simple ideas, all of which involve things that have corresponding images in our imagination. A problem occurs for us, as he progresses, when the object aimed at is Intuitive Knowledge of things which in no way can affect the senses or of which no images can be formed.

======== TEI-P22(20):
Lastly, a thing may be perceived solely through its essence; when, from the fact of knowing something, I know what it is to know that thing, or when, from knowing the essence of the mind, I know that it is united to the body. By the same kind of knowledge we know that two and three make five, or that two lines each parallel to a third, are parallel to one another, etc. The things which I have been able to know by this kind of knowledge are as yet very few.
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    How do we know that two and three make five? Is our knowledge caused by the fact that our senses can allow a modification of our body to represent to our mind for instance, two apples sitting on the table, and three in our hands? We "see" directly that the number of apples considered is the same as five apples. Some might say they know this because they were taught addition in school or they can attempt to reason about this. Both methods may get the "right answer" but Spinoza is saying that we can know directly that two and three make five regardless of the sense objects we might use for examples.

    What about the example of parallel lines? How do we know that the two lines each parallel to a third are parallel to each other? Again we can rely on hearsay, reason, or, so Spinoza expresses, Intuition.

    He develops an example involving proportion between numbers or quantities in which he concludes:

========TEI-P23(21):
...Mathematicians, however, know by the proof of the nineteenth proposition of the seventh book of Euclid, what numbers are proportionals, namely, from the nature and property of proportion it follows that the product of the first and fourth will be equal to the product of the second and third: still they do not see the adequate proportionality of the given numbers or, if they do see it, they see it not by virtue of Euclid's proposition, but intuitively, without going through any process.
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    What does he mean "without going through any process"? Is he not saying that the mind may have direct knowledge as a thinking thing expressing a direct affirmation? What do ideas involve other than affirmation and negation? Ideas are not bodies or images of bodies but are acts of Understanding.

    Spinoza says of Understanding at the end of the TEI:

======= TEI-P108(87):
The properties of the understanding which I have chiefly remarked, and which I clearly understand, are the following:--

I. It involves certainty --in other words, it knows that a thing exists in reality as it is reflected subjectively.

II. That it perceives certain things, or forms some ideas absolutely, some ideas from others. Thus it forms the idea of quantity absolutely, without reference to any other thoughts; but ideas of motion it only forms after taking into consideration the idea of quantity.

III. Those ideas which the understanding forms absolutely express infinity; determinate ideas are derived from other ideas. Thus in the idea of quantity, perceived by means of a cause, the quantity is determined, as when a body is perceived to be formed by the motion of a plane, a plane by the motion of a line, or, again, a line by the motion of a point. All these are perceptions which do not serve toward understanding quantity, but only toward determining it. This is proved by the fact that we conceive them as formed as it were by motion, yet this motion is not perceived unless the quantity be perceived also; we can even prolong the motion so as to form an infinite line, which we certainly could not do unless we had an idea of infinite quantity.

IV. The understanding forms positive ideas before forming negative ideas.

V. It perceives things not so much under the condition of duration as under a certain form of eternity, and in an infinite number; or rather in perceiving things it does not consider either their number or duration, whereas, in imagining them, it perceives them in a determinate number, duration, and quantity.

VI. The ideas which we form as clear and distinct, seem so to follow from the sole necessity of our nature, that they appear to depend absolutely on our sole power; with confused ideas the contrary is the case. They are often formed against our will.

VII. The mind can determine in many ways the ideas of things, which the understanding forms from other ideas: thus, for instance, in order to define the plane of an ellipse, it supposes a point adhering to a cord to be moved round two centres, or, again, it conceives an infinity of points, always in the same fixed relation to a given straight line, or a cone cut in an oblique plane, so that the angle of inclination is greater than the angle of the vertex of the cone, or in an infinity of other ways.

VIII. The more ideas express perfection of any object, the more perfect are they themselves; for we do not admire the architect who has planned a chapel so much as the architect who has planned a splendid temple.
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    So, while we reason through the Ethics we might pause now and then and let our preconceived notions fall away and begin to discover for ourselves what Spinoza assures us is not beyond the reach of our own Understanding.