This appears to be a day of general improvement and reform. No one thing gives greater evidence of it than the fact, that people are inclined to think for themselves on all the important questions of the day. Less bound down by party influence; more inclined to enter into a close examination, and as they investigate they have the moral courage to speak out fearlessly on all matters that concern the public interest. The bonds of party union have become weakened. The intestine divisions and commotions in the prominent parties of our country, give evidence of an approaching revolution. A struggle is at hand, not for the predominance of the stale questions that have been thrust upon the people at the approach of every election, as pledges before nomination, but one of more importance is before us. Who now thinks of making the Bank, the Tariff, the Sub-Treasury, or other matters of like import, a test? These are minor considerations. - The whole country has turned its attention to one subject. The extension or prohibition of Slavery in free territory. or whether we shall sustain the genius of our institutions, or give our support to that ruinous system that is preying upon its very vitals, is the question. All the energies of the Administration and its adherents have been devoted to the last object. An unrighteous war has been waged, under pretence of redress, but virtually for the acquisition of territory, and the extension of Slave power. The interests of the West, by the veto of the River and Harbor Bill, have been sacrificed for the same purpose. If by a war the nation has "conquered a peace." and obtained territory, the Constitution has been violated, the country dishonored, human rights trampled upon and the object consummated by crime, and secured by more money than would have made the purchase at first. But that way to obtain territory would not do. The Mexicans acknowledge the rights of man, as it regards his liberty, and would have stipulated for that in those provinces ceded, if ceded at all. Aggression must be commenced to show that nation her insufficiency to cope with her more powerful neighbor; and thousands of valuable lives have been sacrificed, to obtain that object. This is too obvious to escape notice. It has aroused the indignation of many of the leading men of the North in the Democratic party, who condemn in no measured terms the policy of the Administration. John Van Buren in his speech in the Utica Convention, boldly expressed his sentiments when he said - "The idea of marching, in the 19th century, with the immense power of this free republic, upon an enfeebled and half civilized people, and forcing upon them the institution of slavery which they reject, and make it a fundamental article of a treaty of peace that they shall be guarded against freedom, is so repugnant to my sense of what was due, not merely to the superior magnitude and strength of our own country, but so disgraceful to our free institutions, and so pregnant with evil to the people of both countries that if I could be satisfied that this war is prosecuted to plant human slavery in Mexico, devoted though I am to the glory, honor, welfare and progress of these United States in every pulsation of ray heart, in every breath of my life, in every fibre of my system, so help me God, I would join the Mexicans to-morrow in resisting such oppression." Both the old parties seem to be in a bad fix. A number of aspirants for the Presidency are urged forward by their friends, and we presume a number more hold themselves in readiness for the race; and all are looking with much anxiety for the coming event. The South has thrown down the gauntlet, and require the candidate to pledge his hostility to the Wilmot Proviso, as resolutions passed at almost every Convention in the Slave States attest. Will Northern men take it up and contend for their rights? or will they, as they ever have done, succumb to the slave power, and sacrifice principle to sustain a party. We think the indications rather favorable to the former. Northern men are becoming thoroughly aroused in their feelings. We make another extract from the same speech of John Van Buren. In anticipating the Baltimore Convention, and the reception or rejection of delegates of the faction of the Democratic party of New York State which he adheres to, he says - "I anticipate, therefore, that the delegates, on going to that convention, will be received, and will steadily and strongly declare the views of the democracy of this State, and, in so doing, will secure the nomination of a candidate around whom the republican party of the Union can rally. They will do so, unembarrassed by any instructions or pledges, having no qualifying test prescribed beforehand, and having only to say - 'We represent a certain set of principles; New York has no candidate for the Presidency, and, at least, gratify us so far as to give us a man who will conform to the principles of human freedom, and the faith of the democratic party as it has existed for ages. If you think to bring us down from the platform we stand on, to the miserable, grovelling position you occupy, and suppose that a second Texas case has arisen, you misconceive the position of the State, then and now and do not know the individuals who are to take part in the contest of 1848.' We may assume, therefore, that the delegates will be admitted to the convention; but suppose they are rejected. Then our delegates have nothing to do but to come home under the assurance thus given them by their brethren at Baltimore, that the republican party of the Union is disbanded, and that it is the business of every State to look out for itself." And in this he is not alone; he is backed up by such men as Preston King, Rathbun, and other influential men in the party. Wentworth, of Illinois, Brinkerhoff, of Ohio, Wilmot, of Pennsylvania, and many others of note, have taken a decided stand against the extension of Slavery monopoly. The Whigs, also, seem to have difficulties to surmount. They have two candidates in the field, both slaveholders, and, of course, both pledged to slave interest; for the South requires the same pledge of both parties. Now, how Northern Whigs, who have claimed to be the Anti-Slavery party, many of whom have pledged themselves never again to vote for a slaveholder for President, are to extricate themselves from this dilemma, we have yet to learn. Congress has thrown its influence in favor of oppression, by refusing to lay restrictions on territory acquired, as shown by the loss of that bill in the Senate, and the failure of the Wilmot Proviso, as introduced by Mr. Putnam in his resolution in the House, which was lost by 105 to 92. J. R. Giddings, in his speech on that occasion, in his usual definite style, and high-toned sentiments, remarks, that - "The old lines of party demarcation were obliterated, and we had no longer a Whig party, nor a Democratic party. Sir, the slave party and the party of freedom have been for more than three years in existence, and they are now coming out boldly, and declaring themselves. The line of demarcation is drawn; it has been distinctly drawn to-day. When in 1844 a portion of this body declared that they would go in favor of extending Slavery; when the Executive officers of our Government declared it was the duty of our Government to take under its charge the institution of Slavery, and extend it in foreign lands, then was the issue tendered by the other side of the House, which was accepted by this side." After repeating among other things, that all other questions were looked upon, as of comparatively little consequence, he remarks - "The great question of taking that institution which belonged to Southern States under our peculiar charge has become the great topic, and like Aaron's rod had swallowed up all the rest. He repeated, the slave party has this day declared, by solemn vote which would go down to all coming time, that they had thirteen majority in favor of Slavery and the degradation of our race." We were glad to see among those who recorded their names for freedom, all our members in the House from Michigan, It is a credit to our State, and a lasting honor to them, while our Senators have left a stain upon the fair Peninsula State, and dishonored themselves by giving their influence to slavery. In this state of things in the political world, who can anticipate the result? All is darkness and uncertainty; but the wire-pullers have been and are still at work. The Wilmot Proviso has been laid on the table, hoping by this to avoid the pledge required, and unite the factions. The Ten Regiment bill has passed the Senate and will be urged in the House to gain accession to the slave interest, by securing the influence of aspirants to office. - The war was prosecuted until the end has been obtained for which it was declared. Then stipulations of peace are entered into to heal the dissentions; for however just and desirable it is to ratify a treaty of peace, and put an end to hostilities and a dishonorable war, yet this, with all other parts of the machinery, is made subservient to the Slave power. Now, if Whigs of the North, and Independent Democrats, can be drawn away from their post of duty by such specious pretensions, we think they must have misunderstood the spirit that actuated such men as Giddings, Van Buren, and others. On the independent and decided action of freemen, rests the progress of liberty. If the Proviso has been indefinitely postponed, it is no evidence that the cause is lost. It remains with an intelligent people, (who should not be caught slumbering at their posts,) to teach the servants of thia Republic that in their free suffrage they shall look to its best interests, by elevating to office those who will carry out its leading principles.